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

E. Can and could with see, hear etc.
The verbs see, hear, feel, smell and taste have several different meanings.
When they have their basic meanings of ‘receiving information through the
senses’, they are not usually used in the progressive tenses. Instead of the
progressive tenses, we usually use can with the infinitive of these verbs to
talk about a sense experience that is going on at the moment. Could is used
for the past.
I can see Henry over there. (Compare: I’m seeing Henry off tomorrow)
I can feel something crawling up my leg.
When I got off the train I could smell the sea.

4. May and Can for Permission

A. Asking for Permission
Can, could, may and might are all used in asking for permission.
If you ask in a very simple and direct way, you use ‘can’. It is probably the
commonest of the four.
Can I ask a question?
Can I have a drop more whisky?
Can we have something to wipe our hands please?
‘Could’ is more polite than ‘can’, and is more hesitant than ‘can’, and is used
when you are not sure that you will get permission (or you don’t want to
sound too sure).
Could I just interrupt a minute?
Could I ask you something, if you’re not too busy?
Could we put this fire on?
The negative-interrogative forms can’t I? and couldn’t I? are used to show
that the speaker hopes for an affirmative answer:
Can’t I stay up till the end of the programme?
Couldn’t I pay by check?
‘May’ is also used to ask permission, but this is more formal, though some
people consider that ‘can’ is not correct and that one should say May I...?
‘Might’ is rather old-fashioned and is not often used in modern English.
May I have a cigarette?
May I stop work a little earlier tonight?
Might I take the liberty of pointing out that you are wrong?


B. Giving and Refusing Permission
1. When you want to give someone permission to do something, you use
‘can’.
You can wait in my office if you want.
You can smoke if you like.
She can go with you.
‘May’ is also used to give permission, but this is more formal.
You may leave as soon as you have finished.
You may telephone from here. (a written notice)
‘Could’ and ‘might’ are not used to give permission because they suggest
respect and are more natural in asking for permission than in giving it.
Could I use your phone? - Yes, of course you can.
Might I trouble you for a light? - You may indeed.
2. To refuse permission we use the negative forms:
Can I have some sweets? - No, you can’t.
Members may not bring more than two visitors into the club.
But sometimes we replace the negative answer No, you may not by a
milder expression:
Could we borrow your ladder? - I’m afraid not.
May I see these papers? - I’d rather you didn’t.
We can also use ‘will not’, ‘shall not’ and ‘must’:
I’ll just go upstairs. - You will not.
You shan’t leave without my permission.
Bicycles must not (may not) be left here.