There are two tenses in English – past and present.

英语里有两种时态—过去时和现在时。

The past tense in English is used：

英语里过去时用于：

to talk about the past

谈论过去

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

谈论假设

for politeness.

基于礼貌

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：

在条件状语从句、虚拟语气以及表祝愿时，我们在谈论过去时，经常使用过去完成时。

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：

在一些礼貌的表达中，我们用过去式来谈论现在的事情。

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

I just hoped you would be able to help me.

（实习编辑：于晓伟）