当我们比较的东西在某种程度上（大小、数量、价值等）是相同的或相等的时，使用组合 as … as，它是学习的重点，也是英语四级的常考点。
一、as + 形容词/副词 + as，表示某些东西在某种程度上是相等的，例如：
The world’s biggest bull is as big as a small elephant.
世界上最大的公牛和小象一样大。
The weather this summer is as bad as last year. It hasn’t stopped raining for weeks.
今年夏天的天气和去年一样糟糕。雨已经下了好几个星期了。
You have to unwrap it as carefully as you can. It’s quite .
你必须尽可能小心地打开它。它很脆弱。
二、not as + 形容词/副词 + as，表示某些东西在某种程度上是不相等的，例如：
It’s not as heavy as I thought it would be, actually.
事实上，它并不像我想象的那么重。
Rory hasn’t grown as tall as Tommy yet.
罗里还没有汤米长得那么高。
She’s not singing as loudly as she can.
她唱得不够大声。
They didn’t play as well as they do.
他们打得不如平时好。
当我们想表示被比较的事物之间有很大或很小的差别时，通常可以在 not 后面加 quite，nearly 或 nowhere near，例如：
1、强调大的差异
a. 英国远不及俄罗斯那么大。
England isn't nearly as big as Russia.
England is nowhere near as big as Russia.
相当于 Russia is much bigger than England.
b. 你的鞋比我的贵得多。
My shoes didn't cost nearly as much as yours.
My shoes cost nowhere near as much as yours.
相当于 Your shoes cost much more than mine.
2、强调小的差异
a. 我的公寓没有珍妮的大。
My flat isn't quite as big as Jenny's.
相当于 Jenny's flat is a little / a bit / slightly bigger than mine.
珍妮的公寓比我的稍大一点。
b. 这次旅行没有上次花的时间长。
The journey didn't take quite as long as it did last time.
相当于 The journey took / a bit / slightly longer last time.
上次旅行多花了一点的时间。
当 nearly 或 quite 用于肯定的 as … as 结构时，比较的程度发生变化，例如：
c. David is nearly as tall as Michael.
大卫几乎和迈克尔一样高。
解析：此句强调的是小的差异，相当于 Michael is only a little taller than David.
d. David isn't nearly as tall as Michael.
大卫几乎没有迈克尔高。
解析：此句强调的是大的差异，相当于 Michael is much taller than David.
有的时候，我们还可以用 not so … as，但是 not as … as 更常用，例如：
The cycling was good but not so hard as the cross-country skiing we did.
骑自行车很好，但没有我们越野滑雪那么难。
三、as … as 后面经常跟可能性或能力的表达方式，例如：
Can you come as soon as ?
你能尽快来吗？
Go to as many places as you can.
去尽可能多的地方。
We got here as fast as we could.
我们尽快到了。
四、当比较数量时，as much … as 用于不可数名词，as many … as 用于可数名词，例如：
Greg makes as much money as Mick but not as much as Neil.
格雷格挣的钱和米克一样多，但不如尼尔多。
They try to give them as much freedom as they can.
他们尽量给他们自由。
There weren’t as many people there as I expected.
那里的人没有我想象的那么多。
On the beach, there weren't as many people as I expected.
在海滩上，没有我想象的那么多人。
当涉及到很大的数量时，可以用 as much/many as + 数字，例如：
Scientists have discovered a planet which weighs as much as 2,500 s the weight of Earth.
科学家发现了一颗行星，它的重量是地球的2500倍。
There were as many as 50 people crowded into the tiny room.
有多达50人挤在这个小房间里。
五、as … as 与 quite 和 just 连用，强调两个东西是一样的，例如：
A: You're a terrible tennis player!
你是个糟糕的网球运动员！
B: I'm just as good as you!
我和你一样好！
This phone is quite as good as that one it does cost less.
这部电话和那部一样好，即使它的价钱便宜些。
六、在 not as … as 结构中，It's not 和 It isn't 意思是一样的，例如：
It's not as hard as I thought.
这没有我想象的那么困难。
它等于 It isn't as hard as I thought.