其基本意思为“与…一样”,其中的第一个as为副词,其后通常接形容词或副词(用原级),第二个as可用作介词(后接名词或代词)或连词(后接从句)。使用时应注意以下几点。如:

(1) 在否定句中,第一个 as 也可换成 so。如:

He doesn’t study as [so] hard as his brother. 他学习不如他弟弟努力。

(2) 在该结构的两个as之间通常接形容词或副词的原级,但若涉及数量或程度,可用“as much+不可数名词+as”和“as many+复数名词+as”。如:

You’ve made as many mistakes as I have. 你犯的错误和我犯的一样多。

I haven’t got as much money as I thought. 我不像原来想像的有那么多钱。

其间接形容词时,有时该形容词还可修饰另一名词,但这个名词应带有不定冠词(注意词序)。如:

She is as good a teacher as her mother. 她和她妈妈一样是位好老师。

也可说。如:She is a teacher as good as her mother.

但不说。如:She is as a good teacher as her mother. / They are as good teachers as us.

(3) 第二个as后接从句时,该as通常为连词,但有时这个as还充当其后从句的主语或宾语,此时该as实为关系代词。如:

I gave him as much as he could eat. 他能吃多少,我就给了他多少。

We’ve got food for as many people as want it. 我们的食物,无论多少人吃都够了。

(4) 该结构根据情况可用使用以下修饰语。如:(not) nearly, almost, just, nothing like, exactly, not quite, half, one-ten, twice, three times, 30 per cent等,并且这些修饰语必须置于第一个as之前,而不能置于其后。如:

He doesn’t play half as well as his sister. 他演奏的水平不及他姐姐的一半。

This dress is twice as expensive as that. 这件连衣裙比那件贵一倍。

(5) 若第二个as引导一个表示将来意义的从句,则该从句可用现在时表示将来,也可直接使用将来时态。如:

We’ll get there as soon as you do [will]. 你一到,我们就到。

(6) 在非正式场合(尤其是美国英语中),有时可以省略第一个as。如:

When over forty, he married a woman poor as himself. 他在40多岁时娶了一个像他本人一样穷的女人。

另外,若意思明确,有时可省略第二个as及其后的相关词语。如:

The radios in that shop will be cheaper, but not as good. 那家商店的收音机会便宜些,但质量没那么好。