本站原创[摘 要]As是每年英语高考的热点,常出现在完形填空中,或出现在词汇语法部分,让许多考生头疼.其实,as本身没有多少实在含义,但它的词性较多,也可以搭配成许多词组,并可引导多种从句, 英语学习者非常容易混淆.
[关 键 词 ]as；连词；教学
一、as...as引导比较状语从句
as...as意为“和等一样”,表示同级的比较.使用时要注意第一个as为副词,第二个as为连词.其基本结构为：as+ adj./ adv. +as.如：
This film is as voilent as that one.
This book sells as well as that one.
其否定式为not as/so +adj./ adv. +as.如：
This painting is not as/so valuablel as you think.
若有修饰成分,如a quarter,half ,twice, three times等,则须放在第一个as之前.如：
Your apartment is twice as expensive as mine.
二、引导时间状语从句
作“在等期间,当等的时候”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）表示同一个人的两种动作同时进行,指“一边等一边”. 如： The girl speaks as she has dinner. （2）表示不同的人和物同步发生的动作,指“随着等”.如： As time passed on / by, he became stronger and stronger.
2.while和as从句的谓语动作必须是和主句谓语动作同时发生,when从句的谓语动词可以在主句谓语动作之前、之后或同时发生.（1）从句动作发生在主句动作之前或后,只用 when.如：
She had a rest ,when she had finished her housework.（finished先发生）When I came back,the guests had left already.（e back后发生）（2）主从句动作同时发生,且从句动作为延续性动词时,when,while,as都可使用.When /While /As we were singing,a stranger came in.（sing为延续性动词）When /While /As she was doing her homework,a call was ringing.（do为延续性动词）
三、引导原因状语从句
as,because,since都可以表示因果关系,连接原因状语从句,含义是“因为,由于”,但它们有区别：because语气最强,常用来回答why的提问；since常可译成“既然”；as一般放在句首,语气较弱.如：
He was late because his father was seriously injured.（因为）
Since you he known the secret,what will you do with it next.（既然）
As it rained last night, the gound was wet.（因为）
四、引导让步状语从句
as与although ,though,however ,no matter how,等都可以引导让步状语从句,含义是“虽然,尽管”,但它们有些区别：although语气稍正式些,可放在句首,也可放在句中,主句中不能再用but,但可以用yet；as引导的让步状语从句一定用倒装语序；however引导让步状语从句时,它的后面常跟形容词或副词,However +adj/adv +主语+谓语, 主句.如：
Although my grandfather is 70 years old, he still rides bike every day.
Strange as the ending may seem, the book sells well.
However hard he worked, he couldn’t finish it on time.
5.引导方式状语从句,作“正如,（如）像：解.如：
When at Rome,do as Romans do.
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