动词时态

动词形态可以简单地分为简单式和完成式两种，就能充分掌握所有的时态变化。时间观念有现在式、过去式、和未来式。把be动词抽离出来当做动词看待，其后的分词则视为形容词补语，不放在动词短语里面，如此，整个时态问题就会简单化。

①简单式

简单式的动词可以清楚交代此动作是发生于哪个时段。

一、过去时间

The movable print was introduced to England in 1485.

I was watching TV when I heard the doorbell.

The witness was being questioned in courd when he had a heart attack.

二、现在时间

如果副词是now ，或者真理及事实要用现在简单式

Buch is the U.S. president.

All mothers love their children.

三、未来时间

There will be a major election in March.

The building will be razed next month.

②完成式

从功能上看，简单式是交代动作发生的时段，而完成式并不对动作发生的时段作明确交代，只表示“曾经”“做过”的意思。

一、现在时间（即到现在为止）

I'm sure I have seen this face somewhere.

二、过去时间（即到过去的某个时间为止）

Many soldierd had died from pneumonia before the discovery of penicilin.

I had been smoking three packs of cigarettes a day before I decided to quit.

在盘林西林发生前，许多士兵死于肺炎。

三、未来时间（到将来的某个时间为止）

Next April,I will have worked here for 20years.