as...as意为"和……一样"，表示同级的比较。使用时要注意第一个as为副词，第二个as为连词。其基本结构为：as+ adj./ adv. +as。

as...as的用法

1、接形容词或副词的原级，在否定句中，第一个 as 也可换成 so。

例句：He doesn't study as (so) hard as his brother. 他学习不如他弟弟努力。

2、表示涉及数量或程度，可用“as much+不可数名词+as”和“as many+可数名词复数+as”。

例句：He doesn’t pay as much tax as we do / as us. 他没我们交的税款多。

3、可用(not) nearly, almost, just, nothing like, exactly, not quite, half, one-ten, twice, three times, 30 per cent等修饰，并且这些修饰语必须置于第一个as之前，而不能置于其后。

例句：This room is twice as large as that one. 这个房间是那个房间的两个大。

as…as…的常见句型

1、as…as possible/sb can尽可能的……

例句：

Please answer my question as soon as possible.

请尽快回答我的问题。

The detective is searching the man as carefully as he can.

那个侦探正在尽可能仔细地搜查那个男子的身体。

2、as…as usual/before像以前一样……

例句：

She looks as pretty as before.

她看起来和以前一样漂亮

Though they failed，they still worked as hard as usual.

尽管他们失败了，但他们仍像以前一样努力工作。

3、as long as只要，引导条件状语从句

例句：

I will stay with you as long as there is a room flree.

要是你有一间空余的房子，我就住在你这里。

You may borrow this book as long as you promise to give itback.

只要你答应归还，你就可以把这书借走。