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CAN / MUST / SHOULD
/ OUGHT TO / HAD BETTER |
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The most common modal verbs for talking about permission and obligation are
can / could, must, and should / ought to. |
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1. |
I
couldn't take any photos in the
museum. |
|
2. |
Passengers on the bus
mustn't distract the driver. |
|
3. |
We
should go home on the motorway
– it's much quicker. |
|
4. |
We
ought to go home on the motorway
– it's much quicker. |
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We can use should have or ought to have + past participle to talk about past
events which did not happen and which we regret. |
|
5. |
We
should have gone home on the motorway
– it would have
been quicker. |
|
6. |
We
ought to have gone home on the motorway
– it would have
been quicker. |
|
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Had better is stronger and more urgent than should
/ ought to and is often
used to give strong advice or a warning. It normally refers to the immediate
future. The negative is had better not NOT
hadn't better . |
|
7. |
You'd better post the parcels today or they won't get there in time. |
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HAVE TO / HAVE GOT TO |
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We also use have to to express obligations. It can be used in any tense. |
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1. |
All passengers
will have to fill in an immigration form on arrival. |
|
2. |
You
don't have to tip unless you think the service was excellent. |
|
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We can also use have got to to express obligation, but it is normally used
for specific occasions rather than repeated or general obligations. |
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3. |
I've got to buy a birthday present for my
sister Daniela. |
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NEED |
|
We use need / don't need + to + infinitive to say that something is
necessary or
unnecessary. You can use these forms for habitual, general, and specific
necessity. |
|
1. |
You usually
need to check in two hours before a flight leaves.
|
|
2. |
I
don't need to take a jacket. It's going to be hot today. |
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When we want to say that something is unnecessary on a specific occasion,
we can also use needn't + bare infinitive (without to).
We use don't need to (NOT needn't) for habitual or general necessity,
e.g. Marie doesn't need to wear glasses. Her eyesight is still good.
NOT Marie needn't
wear glasses . |
|
3. |
You
needn't lock the car. Nobody will steal it in this village. |
|
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When something was not necessary, but you did it, we can use
needn't
have + past participle or didn't need to + infinitive. |
|
4. |
We
needn't have booked a table. The restaurant is
empty! |
|
5. |
We
didn't need to book a table. The restaurant is
empty! |
|
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When something was not necessary, so you did not do it, you must use
didn't
need to (you cannot use needn't have to). Pay attention:
NOT We had plenty of petrol so we
needn't have stopped . |
|
6. |
We had plenty of petrol so we
didn't need to stop. |
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BE ABLE TO / BE ALLOWED TO /
BE SUPPOSED TO |
|
We often use be able to or be allowed to + infinitive to talk about what is
possible or permitted instead of can, particularly when we want to use a
form which can does not have. |
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1. |
From tomorrow we
won't be able to park in this street. |
|
2. |
You
are not allowed to smoke in any public buildings in
Argentina. |
|
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Be permitted to + infinitive is used in formal situations, e.g. notices and
announcements, to say what can / can't be done according to the law or to
rules and regulations.
IMPORTANT: We do not use the subject it followed by be allowed to:
NOT It isn't allowed to take
mobiles into the exam room . |
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3. |
It
is not permitted to take mobiles into the exam room. |
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We can also use be supposed to + infinitive to say what people should or
shouldn't do, often because of rules. There is often a suggestion that the
rules are not necessarily obeyed, e.g. Students are not supposed to have
guests after 12.00, but everyone does. |
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4. |
We
are supposed to check in at 3.30. What's the time now?
|
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5. |
You
aren't
supposed to park here – it's a hospital entrance. |
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On the next page you will be able to practise
this grammar. |
