As的用法小结
（一）、 as作连词的用法:
1.作“在…期间，当…的时候”引导时间状语从句.注意与when、 while的用法区别。
①下列情形时,只用as, 而不用when或while。
1)用于表示同一个人的两种动作交替进行,指一边----一边. 如: The girl sings as she goes to school.
He looked behind occasionally as he went forward in the forest.
2)表示两个同步发生的动作或行为,意思是随着…的发展.如: As time went on / by, she became more and more beautiful.
As children get older, they become more and more interested in everything. 3)表示两个短暂行为或事情几乎同时发生.如:I watched her as she read the book. I thought of it just as you opened your mouth. Just as the flying worm hit her face, she gave a loud cry.
4)接名词表示某一个年龄段时.如: As a young man, he was active in sports.
As a little boy (When he was a little boy) he began to learn to play the piano.
②when作"当??的时候"解,可以指较短的(一点)时间,也可指一段时间。 如:When I was at college, I could speak several foreign languages.
When the clock struck twelve, I had slept for 2 hours.
I was wandering through the street when I caught sight of a tailor’s shop有意料之外的意思
③ while常表示一段较长的时间或一个过程,强调主句谓语动词与从句谓语动词同时
如:Work while you work. Play while you play. Strike while the iron is hot趁着
2. As =Since 作"既然"、"由于"解,常用来表示已为人们所知或显而易见的原因或理由。 如: As he’s been ill for ages, I will help him.
As / Since you're not feeling well, you may stay at home. As he wasn't ready, we went without him.
3. As =in the way that作"像"、"按照??的方式"解,引导方式状语从句。如: Do as I told you. Remember, you must do everything as I do. Take the medicine as directed. Maglev trains don’t make much noise, as planes do. When at Rome，do as Romans do．入乡随俗 As in your country，we grow wheat in the north and rice in the South.
4. 用于as--- as或not / so/ as ---- as中,前一个as是副词,后一个as是连词,引导比较状语从句。如:They helped the old as much as possible. I don't speak English so/ as well as she does.
5. 表示虽然,尽管 等,引导让步状语从句,常用倒装语序,模式为: adj. /adv. / n.+as +主语+谓语+主句。如: Tired as they were, they walked on. Child as he is ，he knows a lot．Fast as he ran，he didn't catch the bus．Much as I respect him, I won’t do as suggests. Try as you may, you might fail again Try as he might，Tom could not get out of the difficulties．
6. 表示也------一样。 She is a doctor, as was her husband.
（二）、 as作关系代词,引导定语从句,表示正如,这一点.如:
He is very careful, as we all know. As is well-known, Taiwan belongs to China. 另外,当先行词被the same, such, so等词修饰时,常用as来引导定语从句。如: Such a clever girl as she can learn anything quickly. He wished to be such a man as Lei Feng was．
I was reading the same book as he bought yesterday. This book is not such as I expect Note: He took the police back to the same place where he witnessed the robbery
（三）、as作介词的用法.
1.表示好像。如:He dressed as a policeman. They got united as one man．
2. 表示作为当作。如：I found a job as a guide.
3. 当某人是某身份时。如：As a child , she was sent to abroad.
4. as引导的介词短语大多用作状语,as译为"作为";少数情况可引起宾语补足语。如: As a Party member, I'll take the lead in everything. (状语)
She works as a model. (状语)
She has me as one of her best friends.(引起宾语补足语)
（四）、作副词的用法
1 表示与------等同。如：This dress is twice as expensive as that one.
2 像，如等。As before, he remained unmoved. He doesn't speak English as／so fluently as you．
（3）英语中有很多表示比较的成语。
（4） as black as coal as blind as a bat as brave as a
lion as bright as day as busy as a bee as cold as ice as easy as ABC