# It is comfortable to sit on this chair.



## Alexander Demidov

This is what M.Swan's _Practical English Usage_ (4th ed.) says about it: preparatory _it_ not possible for complements: *It can be used as a preparatory subject, or as a preparatory object **(269)**, but not as a preparatory complement.*_This chair is comfortable _*to sit on*_. _but not _It is comfortable to sit on this chair. _(_to sit on _is the complement of _comfortable_.)
Is it really true? The sentence sounds perfectly OK to me. If it is indeed grammatically incorrect, what about, e.g., "It is easy to see..."? Isn't _to see ... _the complement of _easy_?  228 million Google returns, however, suggest it IS correct.


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## DonnyB

I wouldn't mark it as incorrect, but it's a lot more idiomatic and natural in my opinion to do it as This chair is comfortable to sit on_. _

But I wouldn't raise any objection to something like It's difficult to sit on this chair for any length of time. 

Oh, and welcome to the forum, by the way.


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## Alexander Demidov

DonnyB said:


> I wouldn't mark it as incorrect, but it's a lot more idiomatic and natural in my opinion to do it as This chair is comfortable to sit on_. _
> 
> But I wouldn't raise any objection to something like It's difficult to sit on this chair for any length of time.
> 
> Oh, and welcome to the forum, by the way.


Thank you, DonnyB, for your explanation and welcome. It's a good thing you're doing here..


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## Alexander Demidov

This is the feedback I got from Ardith El-Kareh Fox on Facebook: It's too extreme to say it's not possible to use "It is comfortable to sit on this chair." There's nothing wrong with it; it just sounds quaint and tends to make people think "you're not from around here." No native speaker of American English would normally say or write it as a way to describe a chair by itself, as an isolated sentence. But "It is" constructions can be used to set an atmosphere or mood, in a literary style ("It is pleasant to sit on this chair and gaze out the window)" or to describe an object in a particular context (It's comfortable to sit on this chair when the window is open.)" I could also imagine this sentence being used in a particular (somewhat formal or literary) context such as "My father and grandfather spent many hours in this chair. It is comfortable to sit in this chair."


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## velisarius

DonnyB said:


> But I wouldn't raise any objection to something like It's difficult to sit on this chair for any length of time.



_This chair is difficult to sit on for any length of time. _Not really -  a chair isn't "difficult" - sitting on the chair is difficult, so we prefer to use the impersonal construction with dummy _it _as subject:

_*It's difficult *to sit on this chair for any length of time._

Conversely,

When a chair is comfortable we can easily say:

_This chair is comfortable (to sit on)._

But (although it doesn't strike me as incorrect or even weird),_ *It's comfortable* to sit on this chair  _doesn't tell us that the chair itself is comfortable; it tells us that "sitting on the chair" is comfortable, which is a little odd when you come to really think about it. I might say rather "It's a pleasure/relaxing/convenient to sit on this chair", according to what I really meant.


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## Alexander Demidov

velisarius said:


> But (although it doesn't strike me as incorrect or even weird),_ *It's comfortable* to sit on this chair  _doesn't tell us that the chair itself is comfortable; it tells us that "sitting on the chair" is comfortable, which is a little odd when you come to really think about it. I might say rather "It's a pleasure/relaxing/convenient to sit on this chair", according to what I really meant.


That's an entirely new and unexpected angle of insight, which I find most illuminating. Thank you, velisarius.


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## Chromium

I’m looking at a copy of Swan’s third edition (not the fourth edition cited in the original posting).  I am quite puzzled, as the third edition does not say anything that could be described as "preparatory _it_ not possible for complements."

In fact, regarding how Swan-3rd addresses sentences analogous to "It is comfortable to sit in this chair," Section 446 on the "preparatory it" has a Subsection 446.1 with the heading "It’s nice to talk to you."  The structure of these two sentences is exactly the same: "It is [adjective] [infinitive] [prepositional modifier to infinitive]."  Swan-3rd makes it clear such sentences are correct usage.  Another example he gives: “It’s important to book in advance.”

Indeed, one could cook up hundreds more example variants of the basic structure "It is [adjective] [infinitive]."  "It is enjoyable to stroll along the beach at sunset." "It is advisable to change the oil every 3000 miles."  "It is not comfortable to walk in the hail."  "It’s not easy to go that route."  All perfectly acceptable, although some are a bit formal-sounding.

Was there in fact such a major change to the "preparatory it" section from Swan-3rd to Swan-4th?  I don't think this aspect of English usage has changed much from 2005 to 2017.


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## Chromium

But I think velisarius has zeroed in on the chief issue with the “It is comfortable to sit in this chair” sentence.  As a way to describe a chair and do nothing more, it is redundant.  It’s enough to say “This chair is comfortable.”  Do we really need to be told the additional information that the chair is comfortable specifically for the purpose of sitting on?  As opposed to what? – lying on it, leaning on it, standing on it?  That’s probably what makes the sentence sound a little odd when it appears by itself.  The default assumption is that the assessment of whether a chair is comfortable is in regard to sitting.  Now, if you wanted to say “It’s comfortable to lean on this chair,” there is no redundancy, and nobody will think it sounds strange, except they’ll wonder what’s with you that you can’t just sit on it instead.


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## Alexander Demidov

Chromium said:


> But I think velisarius has zeroed in on the chief issue with the “It is comfortable to sit in this chair” sentence.  As a way to describe a chair and do nothing more, it is redundant.  It’s enough to say “This chair is comfortable.”  Do we really need to be told the additional information that the chair is comfortable specifically for the purpose of sitting on?  As opposed to what? – lying on it, leaning on it, standing on it?  That’s probably what makes the sentence sound a little odd when it appears by itself.  The default assumption is that the assessment of whether a chair is comfortable is in regard to sitting.  Now, if you wanted to say “It’s comfortable to lean on this chair,” there is no redundancy, and nobody will think it sounds strange, except they’ll wonder what’s with you that you can’t just sit on it instead.


Spot on, Chromium, velisarius has indeed nailed it. And yes, Swan's 4th is a major overhaul, with lots of new stuff thrown in, probably without adequate focus-grouping. Well, I, for one, am happy to oblige.


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## Chromium

I had a correspondence with the author, and he agreed that this particular revised section appearing in the 4th edition is not entirely clear.  I found out that the point he wants to make there is that sentences of the type  “It’s heavy to lift this box”  or “It’s lengthy to read this text” are incorrect.  They are indeed incorrect, because “heavy” cannot describe “to lift” and “lengthy” cannot describe “to read.”

However, “It is comfortable to sit in this chair” is not a sentence in this category, because “comfortable” can describe either “to sit in this chair” or “this chair.”

It's incorrect to assume that “comfortable” in this sentence must always, necessarily, be intended by the speaker/writer to describe “this chair” rather than “to sit on this chair.”  It's incorrect to assume that using the word "comfortable" to describe "to sit in this chair" is always odd in all situations.  An example was given above to illustrate this, but here are two additional examples.

A man, while sitting in his usual kitchen chair, just having come home from a long, tiring trip, says to his wife: "It sure is comfortable to sit in this chair again." He's not describing the chair to his wife. He's describing what it feels like for him to sit in it.

In a courtroom, someone points to the chair in the witness box and says: "It's not comfortable to sit in this chair." Again, they are not describing the chair itself, as it might even be physically identical to many other chairs in the room. They are specifically saying that sitting in that chair is uncomfortable, because to sit in it means to be a witness subjected to pressures, intense questioning, and derogatory insinuations during cross-examination.  The chair itself, if placed in another setting, might even be one that could be described as very comfortable.

What these examples have in common is that the phrase “to sit in this chair” carries with it an implied context.

In sum, while “It’s heavy to lift this box” is incorrect under all circumstances, “It’s comfortable to sit in this chair” can be perfectly correct English usage in some contexts.


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## Alexander Demidov

Chromium said:


> I had a correspondence with the author, and he agreed that this particular revised section appearing in the 4th edition is not entirely clear.


Thank you, Chromium, for taking the time and trouble to get to the bottom of it by contacting Mr Swan, getting his input and writing an exhaustive and definitive analysis of the issue in clear and precise language that any student of English can understand.


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## SevenDays

Alexander Demidov said:


> This is what M.Swan's _Practical English Usage_ (4th ed.) says about it: preparatory _it_ not possible for complements: *It can be used as a preparatory subject, or as a preparatory object **(269)**, but not as a preparatory complement.*_This chair is comfortable _*to sit on*_. _but not _It is comfortable to sit on this chair. _(_to sit on _is the complement of _comfortable_.)
> Is it really true? The sentence sounds perfectly OK to me. If it is indeed grammatically incorrect, what about, e.g., "It is easy to see..."? Isn't _to see ... _the complement of _easy_?  228 million Google returns, however, suggest it IS correct.



This "preparatory it" signals that there is _extraposition_ involved, which is the syntactic transformation process that moves an infinitive functioning as subject to the back of the sentence. So, from

_To sit on this chair is comfortable _
we get
_It is comfortable to sit on this char_
with "it" as preparatory subject (also known as "dummy it"). This "it" is necessary so that extraposition results in a grammatical sentence.

The implication is that preparatory/dummy it of course is possible for complements, but perhaps not all complements. Infinitives as "subject" denote a _state of affairs _(a "state" that extends through time)_, _and this "state of affairs" usually represents the "result" of an action, event, etc. And so, being "comfortable" in this chair (and the continuity of this "state" through time) is the result of "sitting" in this chair. By contrast,

_To lift this box is heavy _
is tricky. If your judgment is that the box is "heavy," then it follows that you can't lift the box, and if you can't lift the box, it's hard to conceive a "state of affairs" where you are lifting (and holding) this heavy box. In other words, whereas you can "sit" on this comfortable chair and remain seated (the state of affairs), the box is too heavy to do anything with it. If the infinitive as subject is problematic, then the extraposition

_It's heavy to lift this box _

is problematic as well. But "easy" is ok:

_It's easy to lift this box_

because I can say that sentence while holding the box in my hands.

But isolated sentences are never helpful. What if everyone says, "Hey, don't lift that box. It's too heavy," but you try anyway. Maybe you manage to lift the box _for a millimeter_, and then you drop it. Or you maybe you lift the box and manage to carry it to its proper place, but you struggle (wobbly knees, box pressed against your knees, back arched, etc.). Either way, is "You are right. It _is_ heavy to lift this box" (with emphasis on auxiliary "is") really incorrect? There is continuity (and therefore a state of affairs), even if for a very short amount of time. I suspect that opinions will vary on its acceptability.

Put another way: if the adjective "heavy" refers to the "truth" of a proposition, extraposition is questionable, if unacceptable. But if "heavy" refers to "difficulty" (as in my example, where you manage to lift the box, albeit with difficulty), then extraposition ("it's heavy to lift this box") may be acceptable, at least to some.

(Perhaps Mr. Swan should find a different example, or rethink his statement that "preparatory it" is not possible for "complements." The larger problem is that his book is about _usage, _not _syntax_, or _pragmatics_, for that matter.)


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## Alexander Demidov

SevenDays said:


> _It's heavy to lift this box
> It's easy to lift this box_


Thank you, SevenDays, for you contribution. It does shed some light on the issue. I do, however, have a problem with your examples. I think the pairs to be compared here are "heavy vs light" and "easy vs difficult": the first describes the box, the second the action.


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## Chromium

SevenDays said:


> Either way, is "You are right. It _is_ heavy to lift this box" (with emphasis on auxiliary "is") really incorrect?



Yes, it is incorrect usage.

I understand that it may be confusing.  If “heavy” can substitute for “difficult” in “this is a heavy task we have in front of us,” or “digging trenches is heavy work,” then non-native speakers might wonder why the sentence “it’s difficult to lift this box” can’t be replaced by “it’s heavy to lift this box.”

The reason it can’t is because we native speakers just don’t say that.  Correct and incorrect usage are determined by what native speakers do or do not say, and logic may have little to do with it.  We don’t say “it’s heavy to do these homework problems” or “it’s heavy to dig these trenches” or “it’s heavy to complete this report by the deadline” either.  We do say “it’s heavy work digging these trenches” or “that's a heavy task, completing this report by the deadline.”  Using “heavy” for “difficult” is a metaphorical or idiomatic usage, since only physical objects have weight or density and can therefore be “heavy” in a literal sense.  When it comes to idiomatic and metaphorical usage, some constructions have become standard English, and some have not.  I doubt anyone can say exactly why; it’s just convention.

Dictionaries of collocations can be helpful in these matters.


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## Chromium

SevenDays said:


> Infinitives as "subject" denote a _state of affairs _(a "state" that extends through time)_, _and this "state of affairs" usually represents the "result" of an action, event, etc. And so, being "comfortable" in this chair (and the continuity of this "state" through time) is the result of "sitting" in this chair. By contrast,
> 
> _To lift this box is heavy _
> is tricky. If your judgment is that the box is "heavy," then it follows that you can't lift the box, and if you can't lift the box, it's hard to conceive a "state of affairs" where you are lifting (and holding) this heavy box. In other words, whereas you can "sit" on this comfortable chair and remain seated (the state of affairs), the box is too heavy to do anything with it. If the infinitive as subject is problematic, then the extraposition
> 
> _It's heavy to lift this box _
> 
> is problematic as well.



You've completely lost me on this. Infinitives ("to sit") and gerunds "("sitting") as a subject mean an action; that's all. I don't see how the grammatical correctness of these types of sentences has anything to do with "states of affairs" or "continuity," or whether the action is possible. "To exceed the speed of light is impossible" and "it is impossible to exceed the speed of light" are both 100% grammatically correct.

The problem is simply that "heavy" isn't used to describe "to lift."  There's nothing more to it than that.


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## Alexander Demidov

Chromium said:


> The problem is simply that "heavy" isn't used to describe "to lift."  There's nothing more to it than that.


Except when we are talking about "heavy lifting".


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## Chromium

Alexander Demidov said:


> Except when we are talking about "heavy lifting".



Good point.  That's a collocation in standard usage.  But it can't have a direct object.  "Lifting this box is heavy" remains incorrect.


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## lingobingo

velisarius said:


> _*It's comfortable* to sit on this chair _doesn't tell us that the chair itself is comfortable; it tells us that "sitting on the chair" is comfortable


Just an observation, but if you add a comma, it _does_ mean that, in colloquial usage:

It’s comfortable to sit on, this chair = This chair is comfortable to sit on​It’s easy to write with, this pen = This pen is easy to write with​It’s nice to drive, this car = This car is nice to drive​


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## Alexander Demidov

Chromium said:


> "Lifting this box is heavy" remains incorrect.


It does indeed. Because in a collocation with a "box" and a "lift", "heavy" always refers to the box - at least, that's my reading of it. Here's an example from The Oxford Collocations Dictionary (2nd ed.): The box was so heavy I could barely lift it. There's also a "heavy lift". This is what I found in Oxford Dictionary of English: "weightlifters attempting a particularly heavy lift".


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## Alexander Demidov

lingobingo said:


> Just an observation, but if you add a comma, it _does_ mean that, in colloquial usage:
> 
> It’s comfortable to sit on, this chair = This chair is comfortable to sit on​It’s easy to write with, this pen = This pen is easy to write with​It’s nice to drive, this car = This car is nice to drive​


Ah, the power of a comma!


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## Alexander Demidov

lingobingo said:


> It’s nice to drive, this car = This car is nice to drive​


And by the same token: It's heavy to lift, this box. The grammar here, though, is different, isn't it? The "it" here is not a preparatory it; rather, it's an it in its own right, fulfilling its primary role, i.e., substituting for a noun. Alternatively, it could be referred to as a "fronting it", I suppose, because it "fronts" for a noun (phrase) that is tagged on as an afterthought, for clarification.


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## lingobingo

They’re all the same construction, but in some the adjective modifies the verb: 

It’s {easy to write with}, this pen = This pen is {easy to write with} = Writing [with this pen] is easy ​It’s {nice to drive}, this car = This car is {nice to drive} = Driving [this car] is nice ​
And in others it modifies the noun: 

It’s {comfortable} to sit on, this chair = This chair is {comfortable} to sit on = [Sitting on] this chair is comfortable ​It’s {heavy} to lift, this box = This box is {heavy} to lift = [Lifting] this box is heavy ​​In all of them you could describe the extraposed *it* as standing in for the noun, rather than having no semantic function.


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## Alexander Demidov

lingobingo said:


> They’re all the same construction, but in some the adjective modifies the verb...
> 
> ​And in others it modifies the noun...
> ​In all of them you could describe the extraposed *it* as standing in for the noun, rather than having no semantic function.


I suppose that's one way of looking at it. Yet this "dummy it" here, as you call it, is not the same as preparatory it in, e.g., "It's nice to talk to you" (subject) or "I find it difficult to talk to you" (object), which is what I meant. I'm not sure what it all means in grammatical terms, but I see that in my examples we have a certain grammatical structure where every element is needed to make it whole, while in your examples we have a grammatical structure ("It's comfortable to sit on", where "it" can refer to a "chair" mentioned in a previous sentence), and the tag ("this chair") may but need not be added to the structure for it to be a complete grammatical utterance.


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## lingobingo

I don’t quite get your point. But note that I haven’t called it a dummy *it*, in this instance. What I’m talking about, with the added comma, is a particular colloquial form (possibly not used in AE?), sometimes with the verb added:

It’s comfortable, this chair [is]. / It’s heavy, this box [is].
It’s easy to write with, this pen [is] / It’s nice to drive, this car [is]


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## Alexander Demidov

lingobingo said:


> I don’t quite get your point. But note that I haven’t called it a dummy *it*, in this instance. What I’m talking about, with the added comma, is a particular colloquial form (possibly not used in AE?), sometimes with the verb added:
> 
> It’s comfortable, this chair [is]. / It’s heavy, this box [is].
> It’s easy to write with, this pen [is] / It’s nice to drive, this car [is]


If you don't call it "dummy it", then it's OK, and I don't have any issue with it. But I was responding to your comment as it was emailed to me:




You must've edited it since then. As for the colloquial form, it is covered by M.Swan in his _Practical English Usage_, so I'm quite familiar with it, but only in theory, not using it myself and not hearing it often on the screen or in audiobooks, so your comment was quite an insight for me. Thank you.


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## Myridon

Lingobingo's sentences have a real "it" - "it" refers to the chair - but add "this chair" as a sort of appositive / parenthetical. 
It's comfortable, this chair. = It (this chair) is comfortable.
(This pattern is sometimes used in American English if we realize that we haven't mentioned what "it" is, but it's not used intentionally the way I hear it on British TV shows (He's not very bright, our Tom.).)


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## lingobingo

Yes, I edited it. So there’s not much point in your posting that!


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## Alexander Demidov

lingobingo said:


> Yes, I edited it. So there’s not much point in your posting that!


Well, I'm sure I'm not the first, nor the last, to have responded to a comment as it was emailed to me. A way to avoid this, I suppose, would be to have a notification system that would just alert you to a new post on a thread you follow rather than include its text as well.


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## lingobingo

I confess I wasn’t previously aware that some people get an email the moment you post something! I suppose I should perfect my posts before hitting the button – but I nearly always seem to have second thoughts about something.


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## Alexander Demidov

lingobingo said:


> I confess I wasn’t previously aware that some people get an email the moment you post something! I suppose I should perfect my posts before hitting the button – but I nearly always seem to have second thoughts about something.


It is what it is, lingobingo, that's the nature of the beast: the whole setup for online communication is designed to encourage you to hit the Send button as quickly and as frequently as possible by making it so easy. But what the heck! It's not a War and Peace we are doing here.


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## Chromium

On the subject of the "preparatory it," the "anticipatory it," the "dummy it," and whether there's even a difference between them, I think this brief article is a good starting point: What Is the Anticipatory 'It' in English Grammar?


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## Alexander Demidov

Chromium said:


> On the subject of the "preparatory it," the "anticipatory it," the "dummy it," and whether there's even a difference between them, I think this brief article is a good starting point: What Is the Anticipatory 'It' in English Grammar?


Thank you, Chromium, for this pointer. It's been decades since I consulted any grammar other than PEU, so I'm largely unaware of terminology not used by Mr Swan. He talks about "preparatory it", and that's what I call it. It's instructive to learn that there are nuances here. The umbrella term is probably "dummy pronoun" according to Wikipedia.


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## tunaafi

Alexander Demidov said:


> Thank you, Chromium, for this pointer. It's been decades since I consulted any grammar other than PEU,


I have recommended Swan's_ Practical English Usage_ (3rd edition - I haven't got the hang of the 4th edition yet) to a couple of generations of learners and trainee teachers. Swan is intelligent and knowledgeable, and writes clearly. He does not invent 'rules' that later turn out to have dozens of exceptions; he simply explains clearly what you can and cannot say in modern English. While he is clearly a descriptivist rather than a prescriptivist, he does point out what is not acceptable in standard English, and he has a sounder knowledge of AmE than many BrE writers.

BUT, he is not the go-to book for terminology. His book is a_ practical_ guide not a theoretical one. As far as terminology is concerned, that used by Quirk et al (1985) in their _Comprehensive Grammar of the English Language_  is now widely used and understood in the field of TEFL/TESOL. In the academic world of linguistics, the terminology as defined by Huddleston and Pullum (2002) in their _Cambridge Grammar of the English Language_ is more widely used.


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## Alexander Demidov

tunaafi said:


> Swan is intelligent and knowledgeable, and writes clearly.


He is and he does. I am, however, somewhat baffled by his punctuation: it seems so inconsistent and sometimes even arbitrary - his rules of punctuation notwithstanding. Do you have an opinion on that, tunaafi? Thank you for your comments about terminology. I'll file them away for future reference.


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## tunaafi

Sorry, but talking about punctuation would take us too far off topic.


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## Alexander Demidov

What will it take to get your opinion on the issue? Should I set up a topic entitled "Author's use of punctuation in _Practical English Usage_"?


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## dirudira

[Threads have been merged at this point.  DonnyB - moderator]

I know it quite natural and expected to say 'It is nice to talk to you' instead of 'To talk to you is nice' but then Michael Swan in his Practical English Usage says preparatory it is not possible for complements as in 'It is comfortable to sit on this chair' since 'to sit on' is the complement of 'comfortable'
How do we define the complementary verb usages?
Any help would be greatly appreciated


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## SevenDays

dirudira said:


> I know it quite natural and expected to say 'It is nice to talk to you' instead of 'To talk to you is nice' but then Michael Swan in his Practical English Usage says preparatory it is not possible for complements as in 'It is comfortable to sit on this chair' since 'to sit on' is the complement of 'comfortable'
> How do we define the complementary verb usages?
> Any help would be greatly appreciated


Well, I don't know exactly what Swan is trying to say, because he is _telling _rather than _explaining_. So, if there is more to what he is saying, please quote it.

That said, the issue (as far as I can see), is not about "complements;" rather, the issue is _extraposition_, which in this case means moving an infinitive to the end, adding dummy it as subject. Let's undo extraposition, putting things back to their original wording:

_To sit on this chair is comfortable_

It's not wrong to use the infinitive this way, but this is better (at least to me):

_Sitting on this chair is comfortable_

The reason is simply this: gerunds are more common that infinitives as "subject" when it comes to activities/events. That's why we are more likely to say

_Smoking is prohibited
Swimming is fun
Running with scissors is dangerous_

rather than

_To smoke is prohibited
To swim is fun
To run with scissors is dangerous_

This is a tendency, not a rule.

So, if

_Sitting on this chair is comfortable _
is more common than
_To sit on this chair is comfortable_

then extraposition becomes
_It's comfortable sitting on this chair_
rather than
_It's comfortable to sit on this chair_

There is a "rule" underlying extraposition, but it's a rule regarding "process" (how extraposition happens when it happens). There is no "should" or "must" here, in a prescriptive manner. Thus, you can simply say use "Sitting on this chair is comfortable" and forget about extraposition.


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## dirudira

SevenDays said:


> Well, I don't know exactly what Swan is trying to say, because he is _telling _rather than _explaining_. So, if there is more to what he is saying, please quote it.
> 
> That said, the issue (as far as I can see), is not about "complements;" rather, the issue is _extraposition_, which in this case means moving an infinitive to the end, adding dummy it as subject. Let's undo extraposition, putting things back to their original wording:
> 
> _To sit on this chair is comfortable_
> 
> It's not wrong to use the infinitive this way, but this is better (at least to me):
> 
> _Sitting on this chair is comfortable_
> 
> The reason is simply this: gerunds are more common that infinitives as "subject" when it comes to activities/events. That's why we are more likely to say
> 
> _Smoking is prohibited
> Swimming is fun
> Running with scissors is dangerous_
> 
> rather than
> 
> _To smoke is prohibited
> To swim is fun
> To run with scissors is dangerous_
> 
> This is a tendency, not a rule.
> 
> So, if
> 
> _Sitting on this chair is comfortable _
> is more common than
> _To sit on this chair is comfortable_
> 
> then extraposition becomes
> _It's comfortable sitting on this chair_
> rather than
> _It's comfortable to sit on this chair_
> 
> There is a "rule" underlying extraposition, but it's a rule regarding "process" (how extraposition happens when it happens). There is no "should" or "must" here, in a prescriptive manner. Thus, you can simply say use "Sitting on this chair is comfortable" and forget about extraposition.


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## dirudira

Could you shed some light on this(the screenshot),please


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## entangledbank

The original structure (without 'it') is different in the two cases:

To talk to you is nice. [subject]
This chair is comfortable to sit on. [complement of an adjective]

We normally extrapose from subject position, but can't do so from complement position. The complement sentence would _also_ not be said with a clause as subject:

To sit on this chair is comfortable.

That looks grammatical, but we don't say _sitting_ is comfortable, we say _chairs_ are comfortable.


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## Loob

Swan is talking about:
_This chair is [comfortable to sit on] = This chair is comfortable = This is a comfortable chair._

That's quite different from:
_To sit on this chair is comfortable/Sitting on this chair is comfortable.

------_
Cross-posted.  Etb explains it better but I'll leave this in case it's useful.


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## dirudira

Alexander Demidov said:


> This is what M.Swan's _Practical English Usage_ (4th ed.) says about it: preparatory _it_ not possible for complements: *It can be used as a preparatory subject, or as a preparatory object **(269)**, but not as a preparatory complement.*_This chair is comfortable _*to sit on*_. _but not _It is comfortable to sit on this chair. _(_to sit on _is the complement of _comfortable_.)
> Is it really true? The sentence sounds perfectly OK to me. If it is indeed grammatically incorrect, what about, e.g., "It is easy to see..."? Isn't _to see ... _the complement of _easy_?  228 million Google returns, however, suggest it IS correct.


I have been thinking along the same lines for days, I am afraid I more confused than I initially was.
Just as you said if it is ungrammatical to say 'It is comfortable to sit on this chair what about  sentences like the ones you mentioned


Alexander Demidov said:


> This is what M.Swan's _Practical English Usage_ (4th ed.) says about it: preparatory _it_ not possible for complements: *It can be used as a preparatory subject, or as a preparatory object **(269)**, but not as a preparatory complement.*_This chair is comfortable _*to sit on*_. _but not _It is comfortable to sit on this chair. _(_to sit on _is the complement of _comfortable_.)
> Is it really true? The sentence sounds perfectly OK to me. If it is indeed grammatically incorrect, what about, e.g., "It is easy to see..."? Isn't _to see ... _the complement of _easy_?  228 million Google returns, however, suggest it IS correct.


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## entangledbank

The original poster (now that we're in a merged thread) put three dots at the end of 'It is easy to see...', as if the rest wasn't important. But again we have two different constructions. There are those books where children look for - Wally, isn't it? Here we have the same two choices, only now we can use the same adjective and verb in both:

To see Wally is easy/difficult. [subject]
Wally is easy to see. [complement of adjective]

So we can extrapose out of the subject position:

It is easy to see Wally.


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