The use of modals in English (EFL/ESL Grammar: rules, use, and practice) modals in the past

Before reading this lesson. Please, check the link below about modals in the present. It is an introductory lesson that provides the basics of using modals in the English language.

Modals in the past are not different from modals in the present. Actually, there are the same modal auxiliaries used to refer to past actions and statements.

As you see below, modal auxiliaries in the past take the following form:

I should have completed my exercises.

Subject + modal + have + past participle of the verb

Modals	Used to express	Examples
Had to	Obligation in the past	I didn’t find my book. So, I had to buy it.
Could	Ability in the past	When I was a child, I could run very fast.
Couldn’t	Inability in the past	When I was a child, I couldn’t lift heavy things.
Needed to	Necessity in the past	Yesterday, I went to the grocery store because I needed some tea.
Didn’t need to	Lack of necessity in the past	I didn’t need to call her because I spent all week with her.

Modals	Used to express	Examples
Should have	Advice in the past / regret in the past	You should have done your homework. I should have visited the doctor earlier.
Shouldn’t have	Advice in the past / regret in the past	You shouldn’t have wasted your time. I shouldn’t have said such things to her.
Must have	Obligation in the past	You must have completed your studies.
Must have	Certainty in the past	You must have been tired when you came from work.
Could have	Possibility in the past	I could have chosen Physics. But, I chose Math.
Would have	Willing in the past	I would have gone to the beach If I had had time.
Might have May have	Probability in the past	He was late. he might have visited his friends.
Can’t have	Impossibility in the past	He can’t have been sick. I saw him at the market in the morning
Mustn’t have	Prohibition in the past	You mustn’t have thrown the garbage there. It is a public place.