一、 as作連詞的用法:

　　1. 作"當……的時候",引導時間狀語從句。注意與when、 while的用法區別。

　　① when作"當……的時候"解,可以指較短的(一點)時間,也可指一段時間。如:

　　When he was at college, he could speak several foreign languages.

　　When the clock struck twelve, all the lights in the street went out.

　　② while常表示一段較長的時間或一個過程,強調主句謂語動詞與從句謂語動詞同時發生。如:

　　Work while you work. Play while you play.

　　③ 但屬下列情形時,只用as, 而不用when或while。

　　A) 用於表示同一個人的兩種動作交替進行,指"一邊……,一邊……"。如:

　　The girl dances as she sings on the stage.

　　He looked behind from time to time as he went forward.

　　B)表示兩個同步發展的動作或行為,譯為"隨著……"。如:

　　As time went on / by, she became more and more worried.

　　As children get older, they become more and more interested in the things around them.

　　C)表示兩個短促行為或事件幾乎同時發生。如:

　　I thought of it just as you opened your mouth.

　　Just as the flying worm hit her face, she gave a loud cry.

　　D) 後接名詞表示某一年齡段時,用as。如:

　　As a young man, he was active in sports.

　　2. as=since, 作"既然"、"由於"解,引導原因狀語從句,常用來表示已為人們所知或顯而易見的原因或理由。如:

　　As / Since you're not feeling well, you may stay

as as的用法總結是:中間接形容詞或副詞原級,在否定句中第一個as可為so;若涉及數量或程度可用as much+不可數名詞+as和as many+可數名詞複數+as;該結構修飾語可用almost、nothing like等修飾,修飾語須置於第一個as前等。

1、as...as的用法

as...as意為"和……一樣",表示同級的比較。使用時要注意第一個as為副詞,第二個as為連詞。其基本結構為:as+adj./adv.+as。

2、as引導時間狀語從句

此時,as譯作“當……時候”,可以放在主句之前,也可以放在主句之後。