Ответ:

1.  A cat ______ climb trees.

Correct answer 1:  can

2.  When I was a baby, I _______ sleep all day long.

Correct answer 2:  could

3.  If you lived in the country, you _______ grow your own vegetables.

Correct answer 3:  could

Объяснение:

Modal verb 'can'

Can is an auxiliary verb, a modal auxiliary verb. We use can to:

- talk about possibility and ability

- make requests

- ask for or give permission

The main verb is always the bare infinitive (infinitive without "to").

subject

auxiliary verb

main verb

+

I

can

play

tennis

-

He

cannot/can't

play

tennis

?

Can

you

play

tennis

Can:

Possibility and Ability

We use can to talk about what is possible, what we are able or free to do:

Normally, we use can for the present. But it is possible to use can when we make present decisions about future ability.

Requests and Orders

We often use can in a question to ask somebody to do something. This is not a real question - we do not really want to know if the person is able to do something, we want them to do it! The use of can in this way is informal (mainly between friends and family):

Permission

We sometimes use can to ask or give permission for something:

Modal verb 'could'

Could is an auxiliary verb, a modal auxiliary verb. We use could to:

- talk about past possibility or ability

- make requests

The main verb is always the bare infinitive (infinitive without "to").

subject

auxiliary verb

main verb

+ My grandmother

could

swim.

- She

could not/couldn't

walk.

? Could

your grandmother

swim?

Use of Could

Past Possibility or Ability

We use could to talk about what was possible in the past, what we were able or free to do:

We use could (positive) and couldn't (negative) for general ability in the past. But when we talk about one special occasion in the past, we use be able to (positive) and couldn't (negative).

Requests

We often use could in a question to ask somebody to do something. The use of could in this way is fairly polite (formal).

Answer:

1 — can

2 — could

3 — could