The tense system

The tense system

There are three classes of verbs in English: auxiliary verbs, modal auxiliary verbs and full verbs.
1)- Auxiliary verbs: do, be and have are used as auxiliary verbs to form different tenses.
Do is used to form negative and question forms.
Ex: I don’t understand.
I didn’t agree.
What does she want?
Did they enjoy it?
Do is only used in the positive to give emphasis to a verb.
Ex: She isn’t lazy.
She does try hard.
I did try to phone, but there was no answer.
Is used in question s and short answers:
Ex: He knows I’m here, doesn’t he?
You don’t want to go, do you?
It worked, didn’t it?

Be + ing is used to form continuous tenses.
Ex: Ahmed is writing a book.
We were going for a walk.
We’ll be leaving soon.
+ ed is used to form passive sentences.
Ex: Paper is made from wood.
He was injured in a car accident.
They have been robbed.

Have + ed is used to form perfect tenses:
Ex: I’ve never been there before.
By the time we arrive, they had left.

2)- Modal auxiliary verbs: are auxiliary because they help other verbs, but unlike do, be and have (which only help to form tenses) modal auxiliaries have their own meaning. They express certainty, ability, possibility and advice.
Ex: he must be at least sixty. (certainty)
I can’t swim. (ability)
It might rain this afternoon. (possibility)
You should rest for a few days. (advice)
*The modal auxiliary verbs are: can, could, may, might, will, would, shall, should, must, have to, ought, need.

3)- Full verbs: are all the other verbs in the language for example: go, walk, think, help, eat…