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Understanding and Using Modal Verbs (#35), by Dennis Oliver


Modal Verbs #35:
Individual Modal Verbs



The English modal verbs are often challenging for learners
of English. This happens for many reasons, including both
grammar and meaning.

In this Hint, we'll look at more about must.



Must (#2)



One use for must (negative must not or mustn't) is in showing

Another use is in making conclusions--making guesses which
are based on strong, convincing evidence. These guesses may
be either affirmative ( + ) or negative ( - ).


Akihiro got a very high score on the TOEFL.
must know English well.

(I conclude that Akihiro knows English well
because I know that the TOEFL is very difficult
and I also know that Akihiro got a very high score.)

I'm not sure what time it is, but judging by the sun,
must be around 2:00 PM.

(I conclude that the time is around 2:00 PM because
I know the approximate times for different positions
of the sun.)

There are no lights and no one is answering the doorbell.
must not be at home.

(Because there are no lights and because no one is
answering the doorbell, I conclude that no one is at home.)

When I said, "Could you help me?," that woman had
a blank look and said something in another language.
must not know English.

(I conclude that the woman doesn't know English
because she had a blank look and because she said
something in another language.)



Special Notes:


For negative requirements, both must not and
mustn't are commonly used, but for negative
conclusions, only
must not is commonly used:

You must not do that! / You mustn't do that!
(negative requirement)

You must not be late! / You mustn't be late!
(negative requirement)

He didn't eat his pie. He must not like it.
(negative conclusion)

She looks puzzled. She must not know the answer.
(negative conclusion)


Negative requirements and negative conclusions
have different stress:

You must nt live here! (negative requirement)
mst nt live here. (negative conclusion)

You must nt be tired! (negative requirement)
mst nt be tired. (negative conclusion)

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