Main points

* There are four past tenses – past simple (`I walked’), past continuous (`I was walking’), past perfect (`I had walked’), and past perfect continuous (`I had been walking’).

* All the past tenses are used to refer to past time.

* The past tenses are often used as polite forms.

* The past tenses have special meanings in conditional clauses and when referring to imaginary situations.

1 There are four tenses which begin with a verb in the past tense. They are the past simple, the past continuous, the past perfect, and the past perfect continuous. These are the past tenses. They are used to refer to past time, and also to refer to imaginary situations, and to express politeness.

2 The past simple and the past continuous are used with reference to past time. You use the past simple for events which happened in the past.
I woke up early and got out of bed.

If you are talking about the general past, or about regular or habitual actions in the past, you also use the past simple.
She lived just outside London.
We often saw his dog sitting outside his house.

If you are talking about something which continued to happen before and after a particular time in the past, you use the past continuous.
They were sitting in the kitchen, when they heard the explosion.
Jack arrived while the children were having their bath.

The past continuous is often used to refer to a temporary situation.
He was working at home at the time.
Bill was using my office until I came back from America.

3 You use the past perfect and past perfect continuous tenses when you are talking about the past and you are concerned with something which happened at an earlier time, or which had started at an earlier time but was still continuing.
I had heard it was a good film so we decided to go and see it.
It was getting late. I had been waiting there since two o’clock.

4 You sometimes use a past tense rather than a present tense when you want to be more polite. For example, in the following pairs of sentences, the second one is more polite.
Do you want to see me now?
Did you want to see me now?
I wonder if you can help me.
I was wondering if you could help me.

5 The past tenses have special meanings in conditional clauses and when referring to hypothetical and imaginary situations, for example after `I wish’ or `What if…?’. You use the past simple and past continuous for something that you think is unlikely to happen.
If they saw the mess, they would be very angry.
We would tell you if we were selling the house.

You use the past perfect and past perfect continuous when you are talking about something which could have happened in the past, but which did not actually happen.
If I had known that you were coming, I would have told Jim.
They wouldn’t have gone to bed if they had been expecting you to arrive.