定义： 动词以一定的词形变化形式来表达事物之动作或状态的时间性者称为时态(Tense)。

词形变化的形式共有如下四种：

1.一般式(Simple Form)

2.进行式(Progressive Form)

3.完成式(Perfect Form)

4.完成进行式(Perfect Progressive Form)

动作或状态的时间性则可分为如下三个时段：

1.现在(Present)

2.过去(Past)

3.将来(Future)

这四种词形形式和三个时段可以配合成如下的十二种动词的时态。

这十二种时态可以列表如下：

现以“I”为主语，“do”为动词，把这十二种时态以实例表达如下：(例序即为时态的次序)

1.I do it every day.

(我每天做这样的事。)

2.I did it yesterday.

(昨天我做了这件事。)

3.I shall/will do it tomorrow.

(明天我要做这件事。)

4.I am doing it now.

(现在我正在做这件事。)

5.I was doing it at that time.

(当时我正在做这件事。)

6.I shall/will be doing it at 9：00 tomorrow morning.

(明天早晨九时我会正在做这件事。)

7.I have done it already.

(我已把这件事做好了。)

8.I have done it before I went home yesterday.

(昨天我在回家之前就把那件工作做完了。)

9.I shall/will have done it before you come back tomorrow.

(明天在我回来之前我会把这件工作做好。)

10.I have been doing it for two days.

(这件工作我已做了两天了。──说话时工作尚未做完，所以还得继续做。)

11.I had been doing the work for two hours when the teacher came.

(老师来时那件工作我已做了两小时了。──当时工作尚未完成，所以老师来了我还继续在做。)

12.I shall/will have been doing it for an hour when you come to see me at 9：00 tomorrow morning.

(明天早上九时你来看我时，我会在做那件工作做了一小时。──当然尚未能做完，还得继续做下去。)