Английская грамматика: модальные глаголы

2. We use can + verb in place of the present simple with verbs of perception.

I can see a bird in that tree.

We use could + verb in the place of the simple past with verbs of perception.

I looked up, but couldn’t see anything.

9. Modal verbs. Expressing certainty and possibility

Теория:
Study the information about modal verbs.
Expressing certainty and possibility.
1. If we are certain of our acts, we use be or any full verb.

Jim is at home. Jim works at home.

2. If we are referring to possibility, we use may, might, could + be/have been.

Jane may/might/could be at home now.
Or we use may, might, could + full verb
Kate may/might/could work at head office.

Certain and uncertain answers to questions.
1. A ‘certain’ question may produce an ‘uncertain’ answer.

Does she like apples?- She might (do). She may (do). She could (do). She may not.

2. An ‘uncertain’ question may produce a ‘certain’ answer.

3. We use do/done to replace other verbs, though this is optional.
Will you catch the early train?- I may/I may do.

4. We also answer Wh-questions with ‘certainty’ or ‘uncertainty’.
What is his name?- It’s Brown. It may/might be Smith.

10. Modal verbs. Deduction

Теория:
Study the information about uses of modals to express deduction.

1. We express deduction with must be/can’t be, must have been, can’t/couldn’t have been.

He must be at work. He can’t be out.
2. We use must be in the present to express deduction.

You haven’t eaten for hours! You must be hungry.

3. The negative of must be is can’t be (not mustn’t be).

You have only eaten. You can’t be hungry.