【考点3】as四大语义、四大状语从句（时间、原因、方式、让步状语从句）
【考例】
____ production up by 60%, the company has had another excellent year. (2000 NMET)
A. As B. For
C. With D. Through
2. _______ the day went on,the weather got worse. ('90)
A. With B. Since
C. While D. As
3. Mother was worried because little Alice was ill, especially ____ Father was away in France.(1994 NMET)
A. as B.that C. during D. if
【透视】CDA
1.（表示动作同时发生，意为“随着......，与......同时”)
【超链接】as引导时间状语从句，同while/ when，更强调“一边……一边……”;“随着……”
as与with区别 : 表“随着……”的意思时同with，但with是介词，不可以跟句子。
as 用于引出一个持续性动词表示“在……期间”时，其谓语通常只能是那些含有动作(action)和发展(development) 意味的动词，一般不能是那些不用于进行时态的动词(如 be, seem, love, want, agree, see, know, have 等)，所以下面一句中的 while 不能换为 as：
A：I’m going to the postoffice. 我要去邮局。
B：While you’re there, can youget me some stamps? 当你在邮局时，能帮我买几张邮票吗?
【精练】
1.He was about to tell me the secret ______ someone patted him on the shoulder.
A. as B. until
C. when D. while
2._____the temperature falling so rapidly, we couldn’t go on with the experiment．
A．Since B．With
C．As D．For
3._____private cars are bring us convenience, they may also cause more traffic accidents and pollution.
A. If B. As
C. While D. since
CBC
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