Past perfect (+) s + had + V3 / V ed + c + M s + had + not + V3 / V ed + c + m (?) Had + s + V3 / V ed + c + M?

MODAL VERBS
Modal verbs are used to give additional meaning to the sentence and we use bare infinitive form of a verb after them.
e.g. We clean our room. We must clean our room.
We can clean our room. We have to clean our room.
We may clean our room. We should clean our room.

Verbs which after come after the modals do not take any suffix.

e.g. Jasur should respect himself.
We must take care of our parents.


CAN / COULD
Can is used to express ability to do something in Present Tense.
e.g. Dilshoda can sing beautifully.
Shaxboz can run very fast.
Nigora can read people’s mind
Ashurali cannot do sit-ups.

Could is the past form of can.

e.g. Robert could play tennis well when he was child.
She could not talk in Russian.
Can + not = can’t / cannot
Could + not = could not / couldn’t

Can and could are also used to ask somebody to do something.

e.g. Can you open the window?
Could you come tomorrow.
Can you give me your pen?

Can is also used to ask permission. Could is more polite way of asking than can.

e.g. Can I go with them to football?
Can I sit next to you?
Can we join to your group?

Can is also used to give permission.

e.g. Yes, you can . No, you cannot.
In order to show ability or skill in the future we use can and will be able to.
e.g. In my opinion, I will be able to speak in English.
She can enter the university after finishing the course.

Can is used for general skills or abilities, to be able to is used for particular situations.

e.g. I was able to rescue him from sinking.
They were able to win the match against Liverpool.
Jack could swim well.
My friend was able to fix his laptop when it did not work once.
My friend could fix laptops.