I tried to solve some questions in my textbook.
but I don’t understand well.
I can sleep late tomorrow morning because I _____ go to work.
Whatever you do, you ______ touch that switch. It’s very dangerous.
I wrote “don’t have to” in 1 and “mustn’t” in 2.
but These are incorrect.
I don’t understand the difference between “must” and “have to”.
Please teach me about it!
I agree with your answers!
So what does your text book say, and who wrote it?
The solution of 1 is not “mustn’t” but “don’t have to”
the solution of 2 is not “don’t have to” but “mustn’t”
I don’t know about it
In your first message you say your answers are incorrect.
In your second message you say they are correct.
To clarify, these are the correct solutions:
Have to and must are both used to express obligation in this question. There is a slight difference between the way they are used, and the confusion perhaps comes from the different ways in which negatives and positives are used.
Have to shows us that the obligation comes from somebody else. It’s a law or a rule and the speaker can’t change it.
In the UK you have to buy a TV licence every year.
We use don’t have to to show that there is no obligation. You can do something if you want to but it’s not compulsory.
You don’t have to come with me if you don’t want to.
Must shows us that the obligation comes from the speaker. It isn’t a law or a rule, butit is something that you don’t really have any choice about (and often there will be unpleasant consequences if it is not done).
You must hand in your homework on time.
We use must not (mustn’t) to indicate that there is no choice either, and this is a more commanding phrase than ‘must’
You mustn’t play with poisonous substances.
This is from the BBC Learning English site at bbc.co.uk/worldservice/learn … ge10.shtml
I’m copying the relevant parts in total because I know learners in some countries cannot get the BBC sites:
[i]Confusing ‘mustn’t’ and ‘don’t have to’ is something that I find learners of English often do, perhaps because, from the point of view of meaning, the positive and negative forms of these verbs don’t quite match.
‘Must’ and ‘have to’ are of course what we call ‘modal verbs’ and this category of verbs also includes ‘may’, ‘might’, ‘should’, ‘can’, ‘could’ and so on. There are two things to know about modal verbs:
Firstly, they usually follow a particular grammatical pattern - they’re followed by the infinitive, usually without ‘to’, so: ‘You must go’, ‘I might see him’ and so on.
And secondly, it’s not a bad idea to learn them according to their meaning or how they’re used - their function, if you like. For example, they’re used to show possibility or give permission. And this brings me back to ‘must’ and ‘have to’.
Now, one of the ways that ‘must’ is used in the positive, is when a speaker’s telling you to do something and you really don’t have any choice - it’s an obligation. And here’s an example:
My daughter wants to go out and I say to her,
“Well, you can go out, but you must be back by 8.”
I have the authority, I’m her mother.
I could have said:
“You have to be back by 8” - but that would have been a bit weak. The basic meaning would be the same - still obligation - but it would sound much less strong. Now that’s because ‘have to’ shows obligation more generally - it doesn’t necessarily come from a strong, outside authority. So that’s the positive forms.
But when we come to the negative forms, the difference in meaning is bigger.
For example, if I say to my daughter:
“You mustn’t stay out after 8” that’s my authority, my rule. I’m forbidding her from staying out any later; she has no choice.
So ‘must’, ‘mustn’t’ - there’s a kind of strong authority there.
But if I say:
“You don’t have to stay out after 8”, it’s much weaker - in fact it means something a little bit different. It implies she doesn’t really want to go out and she doesn’t really want to come back after eight and I’m reassuring her that that’s okay; she’s got a choice.
So, ‘don’t have to’ means you don’t need to, you’re not obliged to, it’s not necessary for you to stay out if you really don’t feel like it - you have a choice. [/i]
Thank you for your answer!
I understand the difference between “don’t have to” and “mustn’t”!
I will try to understand the difference between “have to” and “must”!
Thank you!! ^-^
Hi Bangyong,
If you want a simple example of ‘must’ and ‘have to’, look at this:
Why do you have an alarm clock to wake you up in the morning? The reason is that you have to get up early in the morning. This is necessary because you can’t be late for work.
The important thing to remember is that you must set your alarm. This is absolutely necessary to remember because if you don’t do this. you will not hear the alarm.
In the first example the necessity comes from outside (your job) and you can’t change that. In the second example the necessity comes from you because you personally are telling yourself to remember to set the alarm.
Alan
OMG!!! I perfectly understand!
I understand the thing that I didn’t solve!
Really Thanks! Teacher Alan!
Hi all thanks for the interesting article. I never knew there was a difference between must and have to. Here in the US i really think must and mustn’t are falling out of favor. I asked my friends here when they would use must instead of have to and we couldn’t come up with any situations. To me it sounds a little old fashioned or overly fancy. And mustn’t sounds a bit demeaning. You might say it to a small child, your own small child, but I wouldn’t use it even then.
An interesting viewpoint, Luschen. I don’t think there are any such perceptions in the UK.
Hi Luschen,
Did you and your friends also mull over the negatives? There is very definitely a difference in meaning there for me, and I feel certain you would agree:
1. You mustn’t drive drunk.
This means, for example, that driving while intoxicated is against the law and thus not permitted.
2. You don’t have to drive drunk.
This tends to suggest that driving drunk is OK/normal, but you don’t need to do it. The choice is yours – you can do it if you want to. Sentence (2) has no sense at all of the idea that driving while intoxicated is not permitted.
I'd agree with you, though, about not using 'must' (affirmative) very often to talk about necessity/obligation. I'm also far more likely to use 'have to'. I mainly use 'must' in sentences where I draw a logical conclusion:
-[i] Bobby ate some cookies this afternoon. That must be why he isn't eating his dinner; he's not hungry.[/i]
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[i][size=75]“A habit cannot be tossed out the window; it must be coaxed down the stairs a step at a time.” ~ Mark Twain[/size][/i]Hi Amy,
Incidentally, is the difference between “have to” and “must” as clear-cut for you as it seems to be for the BE speakers?
Or do you side with Luschen on this?
Although the examples provided make the difference clear, I wouldn’t say it was clear cut in every situation, Tort. Sometimes one or the other would be used without really considering any definition between the two.
You might well hear:
I have to set my alarm because I must get up early tomorrow
in place of
I must set my alarm because I have to get up early tomorrow.
The example in #1 however, is very clear-cut.
Hi ESL expert. I realize mustn’t and don’t have to are not equivalent in meaning, but still I can’t remember the last time I heard someone say mustn’t. For your example I would say “you shouldn’t drive drunk” or more directly “don’t drive drunk”. In fact that is what the billboards and public service announcements say. I have yet to read a sign that says “you mustn’t drive drunk”.
I can sleep late tomorrow morning because I _____ go to work.
In this blank, according to me, needn’t should appear, rather than mustn’t.
Compare:
Must I wait for you? No, you needn’t.
Need I wait for you? Yes, you must.
That’s right, THL.
I did a search on Google Ngrams for mustn’t in both American and British books - the results are interesting. Ngrams does change mustn’t to must not or I bet the results would be even more dramatic.
books.google.com/ngrams/graph?co … g=3&share=
books.google.com/ngrams/graph?co … g=3&share=
I was surprised at the big drop in usage in British books.