1、作"当……的时候"，引导时间状语从句。
① when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 he was at college,he could speak several foreign languages. （表示636f70797a686964616f31333431353337一段时间）
When the clock struck twelve,all the lights in the street went out. （表示时刻）
② 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发生。
Work while you work. Play while you play.
③ 但属下列情形时，只用as，而不用when或while。
A） 用于表示同一个人的两种动作交替进行，指"一边……，一边……"。
The girl dances as she sings on the stage.
B）表示两个同步发展的动作或行为，译为"随着……"。
As time went on / by,she became more and more worried.
C）表示两个短促行为或事件几乎同时发生。
Just as the flying worm hit her face,she gave a loud cry.
D） 后接名词表示某一年龄段时，用as。
As a young man,he was active in sports.
2、as=since， 作"既然"、"由于"解，引导原因状语从句，常用来表示已为人们所知或显而易见的原因或理由。
As / Since you're not feeling well,you may stay at home.
3、as=in the way that，作"像"、"按照……的方式"解，引导方式状语从句。
He speaks English as Americans do.
4、用于as。as。或not so/ as。as。中，前一个as是副词（副词后面跟形容词、动词、副词），后一个as是连词（连词后面可以跟动词、形容词、句子），引导比较状语从句。
They helped the old man as often as possible.
5、作"虽然"、"尽管"解，引导让步状语从句。常用倒装语序，即adj. /adv. / n.+ as +主语+谓语+主句。
Tired as they were,they walked on.
扩展资料
as的其他用法：
一、as作关系代词，引导定语从句，作"正如"、"这一点"解。
He is very careful,as his work shows.
As is well-known,Taiwan belongs to China.
另外，当先行词被the same,such等词修饰时，常用as来引导定语从句。
Such a clever boy as he can learn anything quickly.
二、as作介词的用法
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。
As a League member,I'll take the lead in everything. （状语）
She works as a doctor. （状语）
They have me as one of their own children.（引起宾语补足语）
一、as作连词的用法 1. as。
as的用法 as。as意为"和……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。
例如： （1）This film is as interesting as that one.这部电影和那部电影一样有趣。（2）Your pen writes as smoothly as mine.你的钢笔书写起来和我的一样流畅。
其否定式为not as/so +adj./ adv. +as。例如： This dictionary is not as/so useful as you think.这本字典不如你想象的那样有用。
若有修饰成分，如twice,three times,half,a quarter等，则须置于第一个as之前。例如： Your bag is twice as expensive as mine.你的袋子比我的贵一倍。
几个关于as。as的常见句型： （1）as。
as possible Please answer my question as soon as possible.请尽快回答我的问题。（2）as。
as usual/before She looks as pretty as before.她看起来和以前一样漂亮。（3）as long as。
（引导条件状语从句） It took us as long as three years to carry out the plan.我们花了长达三年的时间才完成这项计划。（4）as far as He walked as far as the railway station yesterday evening.昨天傍晚，他一直散步到火车站。
（5）as well as She cooks as well as her mother does.她烧菜烧得跟她母亲一样好。一些带有as。
as结构的常见短语归纳： as busy as a bee像蜜蜂一样忙碌 as easy as ABC像ABC一样容易 as deep as a well像井一样深 as light as a feather像羽毛一样轻 as soft as butter像黄油一样软 as rich as a Jew像犹太人一样富裕 2. as用作连词引导时间状语从句 as与when,while都是引导时间状语从句的从属连词，含义都是"当……的时候"。但它们有区别：用when时，从句的动作可以与主句的动作同时发生，也可以先于主句的动作发生；用while时，从句的动作为一过程，主句动作与从句动作同时进行或在从句动作过程中发生；用as时，主句和从句的动作同时发生，具有延续的含义。
例如： （1）It was snowing when he arrived at the construction site.他到达工地时，天正在下雪。（2）He was watching TV while his mother was cooking.他母亲做饭时他在看电视。
（3） You will grow wiser as you grow older.你会随着年龄的增长而越来越聪明。3. as用作连词引导原因状语从句 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表示的语气最强；as一般放在句首，语气较弱，较口语化；since常常用在书面语中，表示多为对方已知的、或稍加分析便可得知的原因，有时可译作"既然"。
例如： （1） He will succeed because he is in earnest.他一定会成功，因为他很认真。（2） Since you are so sure of it he”ll believe you.既然你对此如此有把握，他会相信你的。
（3） As rain has fallen,the air is cooler.因为下过雨，空气比较清爽。4. as作连词引导让步状语从句 as与although （或though）,however （或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所表示的语气较强，引导的让步状语从句用倒装语序；however引导让步状语从句时，它的后面可跟形容词或副词，也要用倒装语序。
例如： （1） Although he is quite old,he still jogs every day.他虽然年纪相当大，仍然每天慢跑。（2） Strange as it may seem,nobody was injured in the accident.这次意外虽然显得令人不可思议，却没有人受伤。
（3） However hard he may try,he will not attain his goal.无论他怎样努力也达不到目标。二、as作关系代词的用法 关系代词as引导定语从句时，既可以单独使用，也可以与其他词连用，其用法要比that和which更为复杂。
1. as引导定语从句与其他词连用 ①用于the same。as结构中 This is the same book as I read last week.这本书和我上周读的那本是一样的。
②用于such。as结构中 I don”t like such books as he recommends.我不喜欢他推荐的那些书。
③用于"so +adj. + a/an + n. （单数） + as "结构中 I am not so strong a man as I was.我已经没有从前那么强壮了。2. as单独引导定语从句 as单独引导定语从句时，先行词可以是一个词，也可以是一个句子或短语。
例如： （1） She is late,as is often the case.她迟到了，这是经常的事。（先行词是整个主句） （2） To shut your eyes to facts,as many of you do,is foolish.对事实视而不见--你们好多人都是如此的愚蠢。
（先行词是不定式短语） 三、as作介词的用法 as作介词，意思是"作为"，"以……身份"。例如： He came to China as a tourist five years ago.他五年前以游客的身份来过中国。
四、as作副词的用法 to the same degree or amount; equally "相同地"，"同样地"。例如： They don”t have as many airplanes.他们没有同样多的飞机。
1.as soon as （一。就）
As soon as I came back,I began to make some meat pies.
我一回来，就开始做肉馅饼。
I will tell him the news as soon as he comes. （只有这句主将从现）
他一到，我就告诉他这个消息。
2.as well as…（ 同。..一样 ），注意这个结构连接两个并列主语，谓语动词和前面那个一致。
Sam as well as I hasmuch work to do.
Sam和我一样，有很多工作要做。（表达的重点在 Sam）
第一个as是副词，第二个是连词
3.
as well as 可以连接主语，也可以连接宾语
He invited you as well as I. I 是主格，所以是和 He 并列的，所以这句话是说：他和我都邀请了你。
4.
as+形容词/副词+as possible （ 尽可能……地 ）
如：
As soon as he saw the monster,Jack ran away as quickly as possible.
Jack 一看到妖怪，就以最快的速度跑开了。
但是：“as long / much as + 名词”可以表示“长达/多达…”的含义。
as做定语从句连接词有两种情况，
第一种是先行词前面有as,so,such,the same修饰的时候，此时as就是用来代替先行词的，如：I want the same book as Jack bought yesterday. as在这里代替book.
第二种情况是，as用来代替整个句子，这时候的定语从句是非限制性定语从句。如：As is often the case,he is late again. 在这个句子中，as代替的就是he is late again这个句子。
②John plays basketball as well as Mike.这里mike 后面需要加does吗？为什么，可以加，但不简简洁.是代动词=plays basketball还有That pencil is as long as this one ，后面需要加is 吗 可以加，但不简简洁I'd like to start my work as early as I could这个句型中as。
as 的用法有错吗？could改为can 这是程度句型= as early(soon) as possible 尽早地④We didn't go as far as the others did.我们走得没有其他人那么远 这里为什么用了一个did?did 代动词，不要最好，前面讲了。
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