Collins Cobuild

participle.

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You should have heard by now that I’m O.K.
They ought to have arrived yesterday.
When  you  want  to  say  that  you  do  not  think  that  something  has
happened, you use ‘should not have’ or ‘ought not to have’, followed
by a past participle.
You shouldn’t have had any difficulty in getting there.
This ought not to have been a problem.
3
You also use ‘should have’ or ‘ought to have’ to say that you expected
something to happen, but that it did not happen.
Yesterday should have been the start of the soccer season.
She ought to have been home by now.
Note  that  you  do  not  normally  use  the  negative  forms  with  this
meaning.
4
When you are fairly sure that something is the case, you use ‘must’.
Oh, you must be Sylvia’s husband.
He must know something about it.
If you are fairly sure that something is not the case, you use ‘cannot’
or ‘can’t’.
This cannot be the whole story.
He can’t be very old – he’s about 25, isn’t he?
 WARNING:  You  do  not  use  ‘must  not’  or  ‘mustn’t’  with  this
meaning.
5
When you want to say that you are almost certain that something has
happened, you use ‘must have’, followed by a past participle.
This article must have been written by a woman.
We must have taken the wrong road.

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To say that you do not think that something has happened, you use
‘can’t have’, followed by a past participle.
You can’t have forgotten me.
He can’t have said that.
6
You use ‘will’ or ‘-’ll’ to say that something is certain to happen in the
future.
People will always say things you want to hear. They’ll manage.
You  use  ‘will  not’  or  ‘won’t’  to  say  that  something  is  certain  not  to
happen.
You won’t get much sympathy from them.
7
 There  are  several  ways  of  talking  about  probability  and  certainty
without using modals. For example, you can use:
• ‘bound to’ followed by the base form of a verb
It was bound to happen.
You’re bound to make a mistake.
• an adjective such as ‘certain’, ‘likely’, ‘sure’, or ‘unlikely’, followed by
a ‘to’-infinitive clause or a ‘that’-clause
They were certain that you were defeated.
I am not likely to forget it.
See Unit
33
for more information on these adjectives.

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