В пособии рассматриваются основные моменты английской грамматики: части речи имя существительное, имя прилагательное и наречие; видо-временные формы глагола; модальные глаголы; неличные формы глагола

C. must (deduction) compared to may/might The difference is best seen by
example:
Imagine that we have three keys on a ring and we know that one of these
keys opens the door. We might begin by picking one key and saying:
This may/might be the key. (Perhaps this is the key.)
But after trying two keys unsuccessfully, we will pick up the third key and
say: This must be the key. No other choice remains.
Similarly, when considering a past action:
He may have come by taxi. (Perhaps he came by taxi but there
are other possibilities).
But He must have come by taxi implies that he had no choice.


D. have/had used for deduction
This is an American usage which is sometimes heard in Britain. have/had
here is chiefly used with to be:
There’s a tall dark-haired boy fishing in the river.
- It has to be/must be George’s son.
had + to be can express the speaker’s feeling of certainty in the past. It can
also be an alternative to must + perfect infinitive:
I wonder who took the money.
- It had to be Tom/It must have been Tom.
He’s the only one who was there.
But to avoid confusion it is advisable to stick to the must forms.


E. can’t and couldn’t used for negative deduction
Negative deduction about a present event can be expressed by can’t/couldn’t
with the simple infinitive of stative verbs or with the continuous infinitive of
dynamic verbs:
You can’t/couldn’t be hungry. You’ve just had dinner.
He says he’s still reading ‘The Murder in the Hotel’.
— He can’t/couldn’t still be reading it. He must be joking.
I lent it to him ages ago and it’s quite a short book.
Negative deduction about a past event is expressed by can’t/couldn’t +
perfect infinitive (simple or continuous):
A man answered the phone. I suppose it was her husband.
It can’t/couldn’t have been her husband. He’s been dead for ages.
To express deduction with the ‘so-called’ double negation negative prefixes
dis- or mis- are used with the verbs or the verb fail:
He can’t dislike the performance. Не может быть, чтобы ему не
нравился…
He can’t fail to recognize her. Невероятно, что он не узнает ее.
He can’t have misunderstood the rule. Не может быть, чтобы он не
понял…
He can’t have failed to recognize her. Не может быть, чтобы он не
узнал ее.