hich 引导非限定性定语从句时，只能位于主句后面吗？
你首先要搞清楚限制性定语从句和非限制性定语从句的区别，然后再把as的用法搞清楚，这样才能知道他们的可比性。s……as
AS +adj(原级)+AS
AS +adv(原级)+AS
as soon as 一……就
as soon as possible 尽可能快地
as early as possible 尽可能早的
as carefully as you can 尽可能认真地
as careful as you can 尽可能认真的
1。as是连词，表示“随着”的意义。lives是life的复数，意义是“生活”。
2。as是连词，表示“因为，由于”的意义。wanting是现在分词，表示主动意义，wanting to buy cars=who want to buy cars。
As的用法小结
as可以作连词、介词及关系代词和副词。现将其用法小结如下:
（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?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)接在名词后面表示某一个年龄段时.如:
As a young man, he was active in sports.
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 2hours.
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发生。如:Work while you work. Play while you play.
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。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.
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: Young as he is, he knows much.
Tired as they were, they walked on.
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.
I was reading the same book as he bought yesterday.
（三）、as作介词的用法.
1.表示好像。如:He dressed as a policeman.
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。如：As before, he remained unmoved.
总之，通过以上的分析，我们对as的词性和用法有了比较全面的理解和把握，才能在实际的运用中做到心中有数，应付自如。限制性定语从句限制所修饰名词或代词的意义，一般说来如把从句去掉句子意思就不清楚，甚至失去意义。而非限制性定语从句主句(句子的其他部分)关系不太紧密，对所修饰名词或代词的意思没有太大影响，把它们拿掉，句子依然很完整，它们可以说是附加上去的东西，而且通常都有逗号把它们和句子的其他部分分开。具体说来，限制性定语从句与非限制性定语从句有以下几个方面的区别：
1. 形式不同限定性定语从句主句和从句之间不用逗号隔开，口语中使用时也不停顿；而非限定性定语从句与主句之间通常 2. 作用不同限定性定语从句用于对先行词的意义进行修饰、限制和识别，如果去掉，就会造成句意不完整或概念不清；而非限定性定语从句用于对先行词起补充说明作用，如果省略，句意仍然清楚、完整： People who take physical exercise live longer.
进行体育锻炼的人活得长些。(若把从句去掉句子就失去意义)
His daughter, who is in Boston now, is coming home next week. 他女儿现在波士顿，下星期回来。(若把从句去句子意义仍然完整)
3. 翻译不同在翻译定语从句时，一般把限定性定语从句翻译在它所修饰的先行词之前，而把非限定性定语从句与主句分开：He is the man whose car was stolen. 他就是汽车被窃的那个人。
I’ve invited Jim, who lives in the next flat. 我请了吉姆，他就住在隔壁。
我请了吉姆，他就住在隔壁。
4. 含义不同比较：I have a sister who is a doctor. 我有一个当医生的姐姐。(姐姐不止一个)
I have a sister ,who is a doctor. 我有一个姐姐，她是当医生的。(只有一个姐姐)
5. 先行词不同限定性定语从句的先行词只能是名词或代词，而非限定性定语从句的先行词则可以是名词或代词，也可以是短语或句子；另外，当先行词为专有名词或其他具有独一无二性的nt: 2.0">Peter drove too fast, which was dangerous. 彼得开车很快，这是很危险的。(which指drive too fast)He changed his mind, which made me very angry. 他改变了主意，这使我很生气。(which指整个主句)Mr. Smith, who is our boss, will leave for Japan LINE-HEIGHT: 18pt; mso-char-indent-count: 2.0">我们的老板史密斯先生下周要去日本。(先行词为专有名词，要用非限制性定语从句修饰)
Her father, who has a lot of money, wishes her to study abroad. 她父亲很有钱，希望她出国学习。(先行词为表独一无二意义的普通名词，要用非限制性定语从句修饰)
6. 关系词不同关系词that和why可用于限制性定语从句中，通常不用于非限制性定语从句；另外，在限制性定语从句中，关系词有时可以省略，而在非限制性定语从句中关系词一律不省略。
打字不易，如满意，望采纳。
1. 引导限制性定语从句时，关系代词which可以与that互换；但引导非限制性定语从句时，只能用which。 例1.She heard a terrible noise, ______ frightened her. A. that B. which C. what D. who 例2.She heard a terrible noise ______ frightened her. A. that B. / C. what D. who 解析： 例1意为：“她听到一个可怕的声音，这使她感到恐惧。”that不能用于引导非限制性定语从句，故选B。例2意为：“她听到了一个使她恐惧的可怕声音。”引导修饰noise的限制性定语从句可以用which或that来引导,故选A。 2. 先行词为reason时，限制性定语可以用why或for which来引导；非限制性定语从句则只能用for which来引导。 例3.I had told them the reason, ______ I didn’t attend the meeting. A. for which B. at which C. for whom D. why例4I had told them the reason ______ I didn’t attend the meeting. A. when B. which C. why D. for that 解析： 例3意为：“我早已把理由告诉他们，于是我没有出席会议。”先行词为reason时，非限制性定语从句应用for which引导，故选A。例4意为：“我已经把为什么没有出席会议的原因告诉他们。”the reason why...是常见搭配，答案为C。 3. 引导限制性定语从句的关系代词在从句中担任宾语时可以被省略；但引导非限制性定语从句的关系代词即使作宾语也不能省略。 例5.He was eager to go to the hospital to see his stepmother,______ he loved and respected as his own mother. A. as B. which C. / D. whom 解析： 本句意为：“他急于去医院看望他的继母，他像对待亲生母亲一样孝敬她。”关系代词whom引导非限制性定语从句并作宾语，不能被省略，故选D。 4．引导限制性定语从句时并作从句宾语的关系代词whom可以用who来代替；但在非限制性定语从句中，whom就不能用who替换。 例6. Do you know Tom, _____ we talked about? A. which B. that C. whom D. who例7.The American journalist ______ the announcer mentioned in the news broadcast is said to have been killed by the gangsters. Which of the following is wrong? A. who B. whom C. whose D. / 解析： 例6意为：“你认识汤姆吗? 我们谈到过他。”应选C。例7意为：“播音员在新闻广播中提到的那位美国记者据说已遭歹徒杀害。下列哪一项是错误的？”关系代词作mentioned的宾语且指人时，可用who/whom/that，在限制性定语从句中可省略，故C是错的。 5．当非限制性定语从句修饰整个主句时，其关系代词可以用as 和which，但位于举句首不能用which，只能用as。此时非限制性定语从句可置于主句之前、之后或之中。 例8______ I expected, he didn’t believe me. A. Which B. As C. That D. When 解析： 本句意为：“正如我所预料的那样，他不相信我的话。”非限制性定语从句修饰整个主句，应用as引导，故答案为B。例9.Mary was late for school,______ often happened. A. as B. for which C. that D. why 解析： 本句意为：“玛丽上学迟到了，这是常有的事。”根据句意，关系代词as引导的非限制性定语从句修饰前面的主句，其位置非常灵活，故答案为A。 6. 由“介词+关系代词”引导非限制性定语从句，关系代词指代整个主句时，不能用as，只能用which，因为有介词关系。 例10.He bought the car for more than $20,000,______ his father was angry. A. about that B. with as C. when D. with which 解析： 本句意为：“他花两万多美元买了这辆车，他父亲对此很生气。”which位于介词with的后面，指代前面的主句，故答案为D。
把这一部分置后也可以He is very shy around strangers, which we all know.
实际上口语中对顺序的要求更宽松，基本没有一成不变的规矩。
一般位于主句后，但有时也可以把主句分开，加在主句中间。前后用逗号分开。
which引导非限定性定语从句，起修饰主句的作用，前加逗号，位于主句之后。
which，非限制性定语从句，放于先行词后面
A
