Modal Auxiliaries

A.    Definition

Modal auxiliaries are helping verbs that express a wide range of meanings. Its also can be used to ask for someone’s permission or help.

B.     Expressing Ability : Can and Could

Can express ability in the present or future.

Formula : S +  Can +  V1 + Complement

Ex :

1.      Bob can play the piano

2.      You can buy  a screwdriver at a hardware store.

Negatif form of can is cannot or can’t

The past form of can is could

Ex : he could walk when he was one years old.

But that is not only its meaning. Another meaning of could is possibility.

Ex: look at those dark clouds..! It could start raining any minute.

C.    Expressing possibility : May and Might, Expressing permission : may and can

May/ might express possibility in the present or future. They have same meaning.

Ex : it may/might rain tommorow.

May is also used to give permission. Ex :

You may borrow my book.

I can have a cookie after dinner.

May I, Could I, Can I                           kinds of modal which can be used to express for someone permission or agreement.

Polite question	Possible answer	Please can come at the end of the questions :may I borrow your pen, please ? Please can be omitted from the question.
May I borrow your pen, please ? Could I please borrow your book ? Can I talk to him ?	Yes, Yes, of course Yes, certainly Of course. Sure (informal) Okay (informal)

Would you, could you, will you, can you                    for expressing someone’s help.

Polite question	Possible answer	the use of can is less formal than the others.
Would you/ could you/will you/can you please open the door?	Yes, Yes, of course Yes, certainly Of course. Sure (informal) Okay (informal)