as 用法一籮筐 日常生活中，有時常需要有「比較」，或者「身為某種身分」你需要怎麼做，那麼 as 就 是你很好的選擇。

雖然 as 意思較多變，易混淆，但我們從「詞類」來分成「兩類」來學 as 的用法：一為介係詞；另一個是連接詞。 

一.介係詞 用法

1.身為…

As a student in Cung-He senior high school, you are supposed to do your homework.

2.當作

This problem is regarded as a challenge. Helen works as a cook in the restaurant.  

二.連接詞用法 

1.和…一樣（用在比較上）

as + 原級（形容詞/副詞）+ as...（和...一樣）

You are not as tall as John, are you?

I can dance as well as Sue (can).

英文有些固定的慣用語，

例如：

as busy as a bee/beaver....像蜜蜂（海狸）一樣忙碌或勤勞

as brave as a lion....英勇如獅子

as blind as a bat....盲目的像蝙蝠

as happy as a lark....和雲雀一樣高興

as slippery as an eel....像鰻一樣滑溜，指狡滑

as cunning as a fox....和狐狸一樣狡猾

as quiet as a mouse....非常安靜

as strong as an ox....非常強壯

as silly as a goose....像鵝一樣笨

as wise as an owl....像貓頭鷹一樣聰明

as easy as pie....很容易

as light as a feather / as light as air....很輕盈

as cold as ice 冷若冰霜

not as/so + 原級（形容詞/副詞） + as... （比...不如...）

I can’t run as fast as you (can).

（否定句中原級形容詞/副詞前的 as 可用 so 代換）

as + 形容詞 + 名詞 + as...（和...一樣）

She has collected as many stamps as her brother (has). 以上的第一個 as 是副詞，第二個 as 是連接詞。括號內的字通常省略。

*as many/much as + 數量 = up to + 數量（有 ~ 之多/多達 ~）

As many as 100 passersby were injured in the accident.

倍數+ as... as（...是...的幾倍）

This table is twice as large as that one.

2.正如同…

Do as I say!

Do in Rome as the Romans do.（入境隨俗）

3.當(=when/while)

As you've finished your work, you may leave any time.

=Since you've finished your work, you may leave any time.

As I stayed there, I had a good time.

=when I ....

=While I.....

I saw Lisa as I was getting off the bus.

4.因為(=since/because)

As we cannot complete with the flood of cheap imported socks, we must strive to produce higher quality products.

As it is late, I decide to go home.

Exercise:

1. _____ you sow, so shall you reap. 種瓜得瓜，種豆得豆！

2. Leave the book ____ it is. 讓書保留現狀吧！

3. You are ____ strong as the superman. 和超人一樣強壯

4. I can’t run ____ fast ____ John. 無法跑得像 John 一樣快

5. Your sister is last ____ usual. 一如往常地

6. As you are in poor health, you should not stay up late. 此處的意思為(A) 正如同…(B) 像... 一樣… (C) 因為 (D) ~的時候

7. As a citizen, you have to pay the tax. 此處的意思為(A) 因為(B) 身為~ (C) 像...一 樣…(D) 正如同…

8. I saw Adam as I was shopping yesterday. 此處的意思為(A) 正如同…(B) 像...一樣… (C) 因為 (D) ~的時候

9. This task is not so hard _____ you think. (A) as (B) than (C) since (D) for

10. Helen, ____ you expect, is not well now. (A) if (B) when (C) so (D) as