Modality: tense

Modal verbs in past, present and future time

Modal verbs do not change in form to make different tenses.

All of the modal verbs can refer to present and future time. Only some of them can refer to past time.

[ready-made pastry is pastry you can buy which is ready to use]

When I was in school, you could get a type of ready-made pastry. I think you can still get it now. (could refers to past time; can refers to present time)

Students on a computer course at the polytechnic will get their own laptops next year. (will refers to future time)

Past and present relations

The modal verbs that only refer to past time are sometimes seen as past forms of the other core modal verbs.

Politeness

We often use the past forms to be more polite or formal, or less direct.

Compare

Can you just have a quick look at the pasta?	Could you just have a quick look at the pasta?	Could is a little less direct.
Will you find me another pen?	Would you find me another pen?	Would is more polite.
You may want to change the formatting.	You might want to change the formatting.	Might is a little more formal and distant.

Reported clauses

We use would, could, should and might as the reported forms of will, can, shall and may in reported clauses.

Compare

what was said	reported
I’ll answer the phone.	She said she would answer the phone.
If we’ve lost the customer’s order, we can’t blame that on anybody else, can we?	He said that if they’d lost the customer’s order they couldn’t blame that on anybody else, could they?
How much food shall I take?	She wondered how much food she should take.
The animals may be there but it may not be easy to see them because they are too small.	They said that the animals might be there but it might not be easy to see them because they were too small.

Past and continuous

We can indicate the past by using a modal verb + have + -ed form of the verb which follows:

We should have listened more carefully.

The fire could have been worse. It could have spread upstairs.

I suppose we could have gone to the hotel. I would have preferred the holiday camp.

We can indicate the continuous by using a modal verb + be + -ing form of the verb which follows.

continuous

They may be coming sooner than we expected.

He could be staying with friends in London.

past and continuous

She might have been waiting for us.

I must have been chatting to him for 20 minutes.