There are two tenses in English – past and present.

The past tense in English is used:

to talk about the past

to talk about hypotheses – things that are imagined rather than true.

for politeness.

There are four past tense forms in English:

We use these forms:

to talk about the past:

He worked at McDonald’s. He had worked there since July.

He was working at McDonald’s. He had been working since July.

to refer to the present or future in conditions:

He could get a new job if he really tried.

If Jack was playing they would probably win.

and hypotheses:

It might be dangerous. Suppose they got lost.

I would always help someone who really needed help.

and wishes:

I wish it wasn’t so cold.

In conditions, hypotheses and wishes, if we want to talk about the past, we always use the past perfect:

I would have helped him if he had asked.

It was very dangerous, What if you had got lost?

I wish I hadn’t spent so much money last month.

We can use the past forms to talk about the present in a few polite expressions:

Excuse me, I was wondering if this was the train for York.

I just hoped you would be able to help me.