# modal verbs of obligation



## mark89

Hi, the modal verb "have to" express obligation (Someone else thinks it is necessary, but not the specker thinks ie is necessary). But In the sentence "You can't turn right here. You have to turn left."  the obligation is express to the specker and don't someone else.


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## PaulQ

Unfortunately, _"Someone else (not the speaker) thinks it is necessary."_ is not true -> "I have to buy some milk or I will not be able to have a cup of coffee." or "You can't turn right here. You have to turn left."


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## mark89

Hi PaulQ, But here say it differetly: http://www.learn-english-today.com/lessons/lesson_cont/verbs/must_have_to.html


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## se16teddy

That page is completely wrong.


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## JustKate

I hate to argue with a source, but I agree with Paul and Teddy. It is absolutely untrue that _must_ means "It's my decision" and _have to_ means "someone is making me do it." I can't imagine who thought this was a rule or even a guideline. We do not differentiate between _must_ and _have to_ "depending on who imposes the obligation."


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## mark89

Hi, so what is difference between "must" and "have to"? Maybe "must" express an obligation more strongly that "have to"; example:

You must try to get some sleep (you are driving and don't have most slept. This is more dangerous)

You must try to get some sleep (It is 2:00. Your flight depart at 6:00 a.m. If don't go to sleep, now, maybe you don't get up early)


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## PaulQ

*Must *can only be used in the present tense: *have to* can be used in all tenses:

1. I *must *be at the meeting by 10:00. I *will *probably *have to* take a taxi if I want to be on time.

2. 
A: You *must *submit a photo with the application otherwise you *will have to* reapply at a later date.
B: I am glad I submitted the photo, otherwise I *would have had to* reapply at a later date.
C: Yes. That's good advice, I did not enclose a photo and I *have had to *make a new application.

3. Before I could escape, I *had to* find a key.

4. *Must *you be so rude? Or *Do *you *have to be* so rude?


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## mark89

Hi PaulQ, I understand that "must" is the difective verb, but that I have said above, is it right?
Actually I am also uncertain for this source: https://www.englishclub.com/grammar/verbs-modals-have-to-must-not-1.htm
is it right?


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## Kirusha

"Have to" doesn't have to be an externally imposed obligation is the sense that somebody other than the speaker formulates it. Rather its "external" nature relates to a lack of compliance on the part of the world: you have to act in a certain way if you want to achieve the desired result because there aren't many other options open to you. You have no choice.

"I have to buy some milk" - I can't drink coffee without milk, but I can't will a carton of milk into existence.
"You have to turn left" - that's the best way to get where you want to be, the world being as it is and you being unable to change that.

Please correct me if you think this is unhelpful, I have to explain this difference to my students, too.


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## Englishmypassion

mark89, as there is no past and future tense of "must", what are you most likely to use instead in those tenses? Have/Had to.


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## mark89

Hi, so if I say: "You must turn left" or "You have to turn left" is the same thing. Have I understood right?

So, are the source, that have found, wrong?


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## Kirusha

I'm also hoping to read native speakers' comments, but here's my stab at it anyway.

I would prefer "You have to turn left here", as a statement of necessity: "that's the best way to get where you want to be, the world being as it is and you being unable to change that".

"You must turn left here" suggests three things two me:
a) it's punishable by law (or equally as bad) to go in the other directions (if you turn right, you'll end up at a military base, will be mistaken for a spy and thrown into jail);
b) the speaker is a patronizing pain in the arse, who always knows better than anyone else;
c) theoretically speaking, "must" is also strong advice, and I had some difficulty inventing a context for it, but here goes: "You must turn left here. They are holding a naked parade here today".


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## mark89

Hi, So, I have understood this: 
"have to" indicates an obligation that derive to  one situation that is a fact;
 example:

I have to work from 8.30 to 5.30 every day. (I don't have chose to work in the this hours )

also "must" indicates an obligation that derive to  one situation that is a fact, but it also indicates personal opinion; 
example:


Mark is a really nice person. You must meet him . I You must meet him.


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## se16teddy

Kirusha said:


> "Have to" doesn't have to be an externally imposed obligation is the sense that somebody other than the speaker formulates it. Rather its "external" nature relates to a lack of compliance on the part of the world: you have to act in a certain way if you want to achieve the desired result because there aren't many other options open to you. You have no choice.
> "I have to buy some milk" - I can't drink coffee without milk, but I can't will a carton of milk into existence.
> "You have to turn left" - that's the best way to get where you want to be, the world being as it is and you being unable to change that.
> Please correct me if you think this is unhelpful, I have to explain this difference to my students, too.


I think there is something in this - _must_ can sound like an imperative or obligation, _have to_ can sound more like a helpful recommendation to achieve a goal. But this is one of those tendencies or gentle nuances that can be very easily overturned by context - especially of course when the function of _have to_ is to cover for defective _must_.


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## Kirill V.

mark89 said:


> Hi, So, I have understood this:
> "have to" indicates an obligation that derive to  one situation that is a fact;
> example:
> 
> I have to work from 8.30 to 5.30 every day. (I don't have chose to work in the this hours )
> 
> also "must" indicates an obligation that derive to  one situation that is a fact, but it also indicates personal opinion;
> example:
> 
> 
> Mark is a really nice person. You must meet him . I You must meet him.



Like Kirusha and se16teddy say,
_you must do something_ is an imperative or obligation
_you have to do something_ - you have to do that to some end (pressed by circumstances)

Neither of these I think work with your example.

_Mark is a really nice person. You *should* meet him

You must meet him _is an order
_You have to meet him = _You need to meet him for some reason, so it is not necessarily that you are going to like the guy


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## se16teddy

_Mark is a really nice person. You *must *meet him.
Mark is a really nice person. You *have to *meet him._
People commonly say both of these, and I can't see any difference between them. It is a kind of flattering hyperbole, implying that you will be losing out badly if you don't meet him.


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## JustKate

kayve said:


> Like Kirusha and se16teddy say,
> _you must do something_ is an imperative or obligation
> _you have to do something_ - you have to do that to some end (pressed by circumstances)
> 
> Neither of these I think work with your example.
> 
> _Mark is a really nice person. You *should* meet him
> 
> You must meet him _is an order
> _You have to meet him = _You need to meet him for some reason, so it is not necessarily that you are going to like the guy



"You must meet him" sounds like an order, and it can be used that way, I'm sure. But it and "have to" are often used *far* more loosely than that to mean "I think it's a wonderful idea for you to meet him." Whether it's an order or not depends entirely - and I do mean entirely - on context.


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## Kirill V.

se16teddy said:


> _Mark is a really nice person. You *must *meet him.
> Mark is a really nice person. You *have to *meet him._
> People commonly say both of these, and I can't see any difference between them. It is a kind of flattering hyperbole, implying that you will be losing out badly if you don't meet him. In that sense, it is imperative.


Okay, thanks! I got it wrong then. 

However...
_Mark is a really nice person. You *must *meet him._ is the same kind of thing as saying _I am *dying* of hunger_. The problem with non-native speakers is that if they do not understand the underlying difference between _must, have to, should_ they are risking to start putting them out of place


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## Kirusha

se16teddy said:


> I think there is something in this - _must_ can sound like an imperative or obligation, _have to_ can sound more like a helpful recommendation to achieve a goal. But this is one of those tendencies or gentle nuances that can be very easily overturned by context - especially of course when the function of _have to_ is to cover for defective _must_.



Sorry, Se16teddy, I'm not with you. What is "defective must"?


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## mark89

Hi, so "must" express obligation without some end,
to my example with "have to":
_Mark is a really nice person. You must meet him (may be you and Mark have an hobby in same. But You must ever go to meet him also if there isn't a reason).

Hi Krisusha, "defective must" mean that  lack of verb temp.

_


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## Kirusha

Oh, I see, I thought it was a term.


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## se16teddy

A "defective" verb is a verb that does not have all its parts. I meant that_ must_ is defective because it lacks an infinitive (and other parts). See definition 3 here: http://www.wordreference.com/definition/defective


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## Kirusha

Thank you. One lives and learns. Can I ask you if you agree with N 12?


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## dipsota

JustKate said:


> I hate to argue with a source, but I agree with Paul and Teddy. It is absolutely untrue that _must_ means "It's my decision" and _have to_ means "someone is making me do it." I can't imagine who thought this was a rule or even a guideline. We do not differentiate between _must_ and _have to_ "depending on who imposes the obligation."



Of course people use both expressions interchangeably but it is true that there is a slight difference between "have to" and "must".
Please don't underestimate what grammarians write


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## JustKate

dipsota said:


> Of course people use both expressions interchangeably but it is true that there is a slight difference between "have to" and "must".
> Please don't underestimate what grammarians write


I'm not underestimating it - I'm discounting it, dipsota. I'm saying that if someone is telling you, "There is a difference between these two, it is a difference that is commonly followed by native English speakers, and I can teach you what it is," that person is wrong.

I'm *really* sorry, but there is no practical difference in meaning between _must_ and _have to_ - nothing that someone trying to use English can count on. Sure, person A might differentiate, and so might person B, but there's no way I can give you any certainty they will differentiate the same way.

Both can be used to issue direct orders. Both can be used informally to say "it would be a really good idea" or simply to indicate enthusiasm. Both can be used to indicate reluctant agreement. In other words, both can be used in exactly the same situations. I'm so sorry, but that is the way it is.


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## velisarius

There's quite a big difference when you come to negate those verbs though, (as noted in the link in post #3). See these old threads:
mustn't v.s don't have to
You don't have to/mustn't pay to see the film.

Also, when you make a mental note that you have to do something it's normal to use "must". For me these sound more natural than if I had used "have to":
_The drains are blocked again, I must get the plumber in. 
I'm going to bake a cake, I must get some eggs and flour.
_
I don't think the_ Learn English Today _advice (post #3) is bad advice, though the differences they perceive are very subtle. Even so, it's seldom the case that  a substitution with the other verb would be positively wrong or not idiomatic.
_
_


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## RM1(SS)

JustKate said:


> I hate to argue with a source, but I agree with Paul and Teddy. It is absolutely untrue that _must_ means "It's my decision" and _have to_ means "someone is making me do it." I can't imagine who thought this was a rule or even a guideline.


I wonder what that person would have thought of "He must have to do that every week."


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## Wordsmyth

dipsota said:


> Please don't underestimate what grammarians write


 This isn't at all a question of grammar, dipsota, but of semantics. And if you're referring to the two sources quoted in this thread, then neither appears to have been written by a grammarian anyway. (See below.)



mark89 said:


> So, are the source, that have found, wrong?


 Obviously the authors of those sources think they're right, so for themselves they are right. If they claim to represent the usage of over 360 million native English speakers, then they are wrong.

You may find other internet sources that quote this bizarre theory (or very subtle perception of differences, if you prefer, Veli) about "must" and "have to", but remember, much of what you find on internet is just copied from another internet source. It may have started life as just one person's whim.

When you use an internet 'language teaching' site, it's always a good idea to check on the background of the author(s), to see whether what they say is based on any kind of in-depth 'real world' research or reasoning, or whether it's just one person's unsubstantiated opinion.

On the 'Learn English Today' site you can find this about the author: _"There is no team behind this website, just me and my computer in my spare time.  My name is Kathleen, also known as Kate." _So it's just Kate and her computer (and absolutely not _our_ JustKate and her computer!). I've found nothing on the site that gives its views any more 'authority' than an individual's post on this forum might have.

The EnglishClub site is less forthcoming about who writes what within the site. The founder (according to other sources) has a background in publishing and photography. Nowhere in the site's articles could I find any reference to the background of the views expressed, nor cross-references to more widely recognised sources. I leave you to draw your own conclusions.

Ws


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## dipsota

JustKate said:


> I'm not underestimating it - I'm discounting it, dipsota. I'm saying that if someone is telling you, "There is a difference between these two, it is a difference that is commonly followed by native English speakers, and I can teach you what it is," that person is wrong.
> 
> I'm *really* sorry, but there is no practical difference in meaning between _must_ and _have to_ - nothing that someone trying to use English can count on. Sure, person A might differentiate, and so might person B, but there's no way I can give you any certainty they will differentiate the same way.
> 
> Both can be used to issue direct orders. Both can be used informally to say "it would be a really good idea" or simply to indicate enthusiasm. Both can be used to indicate reluctant agreement. In other words, both can be used in exactly the same situations. I'm so sorry, but that is the way it is.



I understand what you are saying, JustKtake.  That is why I wrote that I know people use both expressions interchangeably. What I wanted to express is that the explanation of 'the slight difference' is written in books on grammar.
I didn't mean to upset you. If I did,  please accept my aplogies.


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## dipsota

Wordsmyth said:


> This isn't at all a question of grammar, dipsota, but of semantics. And if you're referring to the two sources quoted in this thread, then neither appears to have been written by a grammarian anyway. (See below.)
> 
> Obviously the authors of those sources think they're right, so for themselves they are right. If they claim to represent the usage of over 360 million native English speakers, then they are wrong.
> 
> You may find other internet sources that quote this bizarre theory (or very subtle perception of differences, if you prefer, Veli) about "must" and "have to", but remember, much of what you find on internet is just copied from another internet source. It may have started life as just one person's whim.
> 
> When you use an internet 'language teaching' site, it's always a good idea to check on the background of the author(s), to see whether what they say is based on any kind of in-depth 'real world' research or reasoning, or whether it's just one person's unsubstantiated opinion.
> 
> On the 'Learn English Today' site you can find this about the author: _"There is no team behind this website, just me and my computer in my spare time.  My name is Kathleen, also known as Kate." _So it's just Kate and her computer (and absolutely not _our_ JustKate and her computer!). I've found nothing on the site that gives its views any more 'authority' than an individual's post on this forum might have.
> 
> The EnglishClub site is less forthcoming about who writes what within the site. The founder (according to other sources) has a background in publishing and photography. Nowhere in the site's articles could I find any reference to the background of the views expressed, nor cross-references to more widely recognised sources. I leave you to draw your own conclusions.
> 
> Ws



When I mentioned 'grammarians' I referred to rules written by Angela Downing, Quirk, Jespersen,  among others.  As I said before,  I know both expressions are used interchangeably .  Kind regards.


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## JustKate

dipsota said:


> I understand what you are saying, JustKtake.  That is why I wrote that I know people use both expressions interchangeably. What I wanted to express is that the explanation of 'the slight difference' is written in books on grammar.
> I didn't mean to upset you. If I did,  please accept my aplogies.


No, no - I am not in the least upset. Well, actually, I do get a bit upset, but it's at those sources that say anything as flat-out wrong as "They are used differently depending on who imposes the obligation." That's deceptive. And it's a disservice to learners.

I don't even know that I can concede there is a "slight difference" (aside from the tense difference identified by Paul in post #7). A slightly different nuance, maybe - but most of the nuance is conveyed by tone of voice and other cues, cues that aren't available in writing. You can't read a sentence such as "You have to turn left" and know whether the speaker meant "You are required to turn left - I am ordering you to turn left" or "I think it's a really, really good idea to turn left." The words just won't convey that information.

Velisarius makes a good point about the negative forms, though.


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## dipsota

JustKate said:


> No, no - I am not in the least upset. Well, actually, I do get a bit upset, but it's at those sources that say anything as flat-out wrong as "They are used differently depending on who imposes the obligation." That's deceptive. And it's a disservice to learners.
> 
> I don't even know that I can concede there is a "slight difference" (aside from the tense difference identified by Paul in post #7)/. A slightly different nuance, maybe - but most of the nuance is conveyed by tone of voice and other cues, cues that aren't available in writing. You can't read a sentence such as "You have to turn left" and know whether the speaker meant "You are required to turn left - I am ordering you to turn left" or "I think it's a really, really good idea to turn left." The words just won't convey that information.
> 
> Velisarius makes a good point about the negative forms, though.


I´m glad that you are not upset.  Kind regards.


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## Wordsmyth

dipsota said:


> When I mentioned 'grammarians' I referred to rules written by Angela Downing, Quirk, Jespersen, among others.


 Thanks for clarifying that, dipsota. At least you weren't thinking of random websites! I doubt, though, that those linguists would consider they were writing 'rules'. I imagine that they were making observations about perceived tendencies in certain contexts. It may be that, statistically, they have found that "must" has tended to be used more often for subjective obligation, and "have to" more often for objective obligation. That may be of interest in certain academic linguistic analyses, but it's of little or no use in understanding how a particular speaker may be using "must" or "have to".

It's also of no use when teaching learners how to express obligation, because they'll waste their time worrying about which to use, when in fact there's no _intrinsic_ difference between the two. (See marc89's various posts, seemingly inspired by so-called teaching sites' misrepresentation of an observed (limited?) tendency as if it were an absolute rule of language.)

Imagine two different roads between two towns. Each is as quick and easy as the other. A study shows that 60% of traffic takes road A, and 40% takes road B. It doesn't make A any more legitimate a road than B. It doesn't mean A is a better road than B. The split may be due to random factors. And it doesn't provide a basis for recommending one road or the other to someone who's new to the area. (For the journey, read "subjective obligation", for A and B, read "must" and have to".)

I fully agree with Kate:


JustKate said:


> ... those sources that say anything as flat-out wrong as "They are used differently depending on who imposes the obligation." That's deceptive. And it's a disservice to learners.



Ws
_[Edit: typo]_​


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## mark89

se16teddy said:


> A "defective" verb is a verb that does not have all its parts. I meant that_ must_ is defective because it lacks an infinitive (and other parts). See definition 3 here: http://www.wordreference.com/definition/defective



Hi se16teddy, what do you mean to say that: "_must_ is defective because it lacks an infinitive"?


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## SReynolds

You can't say _I'm going *to must* do it_ because _must_ is a _defective verb, _its conjugation is lacking: it has no future, conditional, subjunctive and (for all intents and purposes) past form (_technically speaking, must_ itself is the past tense of _must_, its use is mostly literary).

You usually replace _must_ with _have to_ or _need to_ when you can't use _must_, which are not defective. This should already tell you that these two forms are pretty much equivalent.


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## mark89

Hi SReynolds, I am agree to you on the definition of a defective verb.  I  did wan to also a confirmation.


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## mark89

kayve said:


> Like Kirusha and se16teddy say,
> _you must do something_ is an imperative or obligation
> _you have to do something_ - you have to do that to some end (pressed by circumstances)
> 
> Neither of these I think work with your example.
> 
> _Mark is a really nice person. You *should* meet him
> 
> You must meet him _is an order
> _You have to meet him = _You need to meet him for some reason, so it is not necessarily that you are going to like the guy



But is should  watch like an verb of obligation?


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## PaulQ

mark89 said:


> But is *should *a verb of obligation?


It can be a weaker form of 'must' - If you see a notice that says "Passengers should not lean out of the window." then *should *almost has the power of must.

However, in "You should meet David." *should *is an encouragement to meet David, not an obligation.

Then there is "Should you want something to eat, there is food in the refrigerator." where *should *is the subjunctive future = "If you were to..."


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## mark89

Hi PaulQ, So in your sentence "Passengeres should lean tou of the windows" is a oblgattion. But in my sentence: _Mark is a really nice person. You *should* meet him" is an advice. have I understood right?_


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## PaulQ

Exactly!


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## mark89

So Do everything depends to the contex?


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## PaulQ

mark89 said:


> So, Do does everything depends to the context?


Yes. If someone says "You should do XYZ." and you do *not *do XYZ, then you must have a reason not to do XYZ. However, *the strength of the reason will depend on the authority of who is saying the sentence. *

*Judge in a Law Court*: "Mark89, you should pay PaulQ €2,000." -> this means "you *must* pay PaulQ the money, [otherwise you will go to prison.] If you do not give PaulQ €2,000, you must have the very best reason.
*Friend*: "You must meet Louisa, she is very pretty." means, "I strongly encourage you to meet Louisa [please do this.]" If you do not meet Louise, you should have a good excuse.
*Man in the Street selling Toys*: "You should buy one of these, sir. They are beautiful." -> "I am trying to get your money by making you feel as if you ought to buy one - there is no real obligation." -> You don't need a reason not to buy the thing.


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## mark89

Hi, so the modal verb "must", "have to" and "should" are verb of obligation when  the authority of who is saying the sentence is strongly or you have said no will take to grave consequence; example:

"you must turn left" (because to right there is a river) 

if I have understood right, so in your sentence:  "You must meet Louisa, she is very pretty."  "must" is not an obligation.


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## PaulQ

"You must meet Louisa, she is very pretty." "must" is not an obligation.


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## mark89

So, in you sentence: "Mark89, you should pay PaulQ €2,000." might  I put "must"?


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## PaulQ

Yes. Judges have a lot of authority.


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## mark89

Hi,so, It is most correctly put, in the sentence with the Judges, "must" that should.


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## PaulQ

Yes.


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## mark89

So, in this sentence: "Last week Tina broke her arm and had to go to hospital." "have to " represents a impersonal obligation, if obligation is express to the doctor. But if the obligation is express to myself, so "have to" represents a personal obligation. Have I understood right?


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## SReynolds

I don't think it's a good idea to talk about _impersonal_ and _personal_ obligations, it makes a very simple problem a lot more complicated than it should be. Both _must_ and _have to_ can be used for both types of obligations. _Should_ is used to give advice but, like in every other language, there are softeners and _should_ can be used when the thing mentioned is actually necessary.

English is just like every other language, I'm pretty sure that these things are not unique to the two languages I speak fluently.


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## sound shift

mark89 said:


> So, in this sentence: "Last week Tina broke her arm and had to go to hospital." "have to " represents a impersonal obligation, if obligation is express to the doctor. But if the obligation is express to myself, so "have to" represents a personal obligation. Have I understood right?


Going to hospital was a necessity, and not an obligation in any moral sense. "Have to" is often used for needs, e.g. "I've got to get some milk this morning", where no one has told me to buy some milk and I'm thinking that if I don't buy any milk we will run out of milk.


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## mark89

So,  a personal obligation is a necessity and impersonal obligation is only obligation;
example:
"I have to wear glasses for reading." It indicate a necessity.
"In London, you must  drive on the left side". It indicate a necessity.


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## PaulQ

What do you see as the difference between:


"I have to wear glasses for reading." 

"Where are my glasses? I'm old and I must wear glasses for reading."
"Do I have to wear glasses for reading?" <- asked of an optician for general information.

"Do I _*have *_to wear glasses for reading?" <- asked of an optician with emphasis on "have".

"Must I wear glasses for reading?" <- asked of an optician for general information.

"*Must *I wear glasses for reading?" <- asked of an optician with emphasis on "must."?


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