Modal in The Past Form

The other class of auxiliaries is made up of the ones in the illustration. The function only as auxiliaries and do not change grammatical form in the way verbs do. These are called modal auxiliaries. Some of them do function as the past the past tense form of some of the others. May changes to might, will to would, can changes to could, and shall changes to should.

Modal in the Past Form

Modals
Present	Past
Can	Could
Will	Would
Shall	Should
May	Might

1.       Could + Verb base

v  To express ability to do something

Example : I could speak English

v  To express ability, subject to certain conditions which probably do not exist.

Examples : I could go now, if I wanted to ( I don’t want to )

                 When I was sixteen, I could dance all night ( If circumstances permitted)

v  To express polite question

Example : Could I go to the cinema, please ?

v  To express polite request

Examples : Could you wait a moment, please ?

v  To express polite offer

Example : I could lend you my car till tomorrow

v  To express polite suggestion

Example : Could we visit Grandma at the weekend ?

v  To express possibility

Example : It could get very hot in Montana

2.       Would + Verb base

v  To express wish, request ( more polite than will )

Example : would you shut the door, please ?

v  To express habits in the past

Example : Sometimes he would bring me some flowers.

v  Insert rather into the pattern and use this expression to express preferences

Example : I would rather visit Italia than Paris 

3.       Should + Verb base

v  To give definite advice ( advisability )

Example : You should drive carefully in bad weather

v  To express the subject’s obligation or duty

Examples : You should switch off the light when you leave the room.

They shouldn’t allow parking here, the street is too narrow.

4.       Might + Verb base

v  To tell possibilities

Examples : It might rain today

                I might accompany you, but it does not appear very likely

v  To express polite request

Example : Might I borrow your coat ?

v  To express hesitant offer

Example : Might We help you ?