as的用法

　 as可用作連詞,引導比較、時間、原因及方式等四種狀語從句,應注意的是,引導的比較狀語從句往往有省略;引導的時間狀語從句一般用一般現(xiàn)在時而不用一般將來時;引導原因狀語從句時與“Because”和“since”引導的從句比較起起來語氣最弱.

　　as作介詞,意思時“作為”,“以……身份”.例如：He came to China as a tourist five years ago.

　　而表示像…一樣時,like通常作介詞用,而介詞后面通常接名詞,代名詞和動名詞.
現(xiàn)將其用法小結如下:

　　(一)、 as作連詞的用法:

　　1.作“在-------期間,當----的時候”引導時間狀語從句.注意與when、 while的用法區(qū)別.

　?、傧铝星樾螘r,只用as,而不用when或while.

　　1)用于表示同一個人的兩種動作交替進行,指一邊----一邊.如:

　　The girl sings as she goes to school.

　　He looked behind occasionally as he went forward in the forest.

　　2)表示兩個同步發(fā)生的動作或行?意思是隨著-----的發(fā)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)表示兩個短暫行為或事情幾乎同時發(fā)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)接在名詞后面表示某一個年齡段時.如:

　　As a young man,he was active in sports.

　?、趙hen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 I was at college,I could speak several foreign languages.When the clock struck twelve,I had slept for 2hours.

　?、?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(fā)生.如:Work while you work.Play while you play.

　　2.As =Since 作"既然"、"由于"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 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,引導方式狀語從句.如:

　　Do as I told you.

　　Remember,you must do everything as I do.

　　4.用于as--- as或not / so/ as ---- as中,前一個as是副詞,后一個as是連詞,引導比較狀語從句.如:They helped the old as much as possible.

　　I don't speak English so/ as well as she does.

　　5.表示雖然,盡管 等,引導讓步狀語從句,常用倒裝語序,模式為:

　　adj./adv./ n.+as +主語+謂語+主句.如:Young as he is,he knows much.

　　Tired as they were,they walked on.

　　6.表示也------一樣.She is a doctor,as was her husband.

　　(二)、 as作關系代詞,引導定語從句,表示正如,這一點.如:

　　He is very careful,as we all know.

　　As is well-known,Taiwan belongs to China.

　　另外,當先行詞被the same,such等詞修飾時,常用as來引導定語從句.如:

　　Such a clever girl as she can learn anything quickly.

　　I was reading the same book as he bought yesterday.

　　(三)、as作介詞的用法.

　　1.表示好像.如:He dressed as a policeman.

　　2.表示作為當作.如：I found a job as a guide.

　　3.當某人是某身份時.如：As a child ,she was sent to abroad.

　　4.as引導的介詞短語大多用作狀語,as譯為"作為";少數(shù)情況可引起賓語補足語.如:

　　As a Party member,I'll take the lead in everything.(狀語)

　　She works as a model.(狀語)

　　She has me as one of her best friends.(引起賓語補足語)

　　(四)、作副詞的用法 1 表示與------等同.如：This dress is twice as expensive as that one.2 像,如等.如：As before,he remained unmoved.

　　總之,通過以上的分析,我們對as的詞性和用法有了比較全面的理解和把握,才能在實際的運用中做到心中有數(shù),應付裕如.