5.由as和as if/as though引导的表语从句

Air to us is as water is to fish．

空气对于我们就像水对于鱼儿一样。

提示：

此句中的as可以用what替代。(见本节的说明)

Engines are to machines as/what hearts are to animals．

发动机之于机器犹如心脏之于动物。

All this was over twenty years ago，but it's as though it was only yesterday．

这都是20多年前的事了，但宛如昨天一样。

It looked as if it was going to rain．

看起来天要下雨了。

It seems as if he knew every student of his．

似乎他认识他的每个学生。

He looks as if he were very sleepy．

他看上去很困。

She looks as if she would cry．

她看起来好像要哭了。

提示：

由as if和as though引导的表语从句的虚拟语气的用法参见虚拟语气。