as是英语中用得非常广泛而且极其活跃的一个词。它可以作介词、副词、连词和联系代词，还可以同其他的词搭配，构成一些固定的词组和句型，表达多种意思。本文仅对as构成的一些常用句型进行归纳。
一、状语从句中的as
1.时间状语从句
as引导时间状语从句，表示主句动作和从句动作同时发生，可译为“随着”“一边……一边……”“当……时候”。如：
She was reading something as she was waiting for the bus to come.
例1 ________ time going by，it becomes colder and colder.
A. As B. When C. With D. When
解析：这是with的复合结构，宾语后面的宾语补足语应为going by，与宾语构成主动联系，因而选C。此题易误选A，但要注意as为连词，若选A，此处应为as time goes by。
2.原因状语从句
as 引导原因状语从句，表示明显的原因或已知的事实。如：
As I’m so ashamed of my body，I’m trying to lose weight.
例2 We had to walk all the way，________ we had no money for fares.
A. while B. as C. when D. although
解析：仔细略论句子我们不难发现，主句与从句为因果联系，因而选B。
3.让步状语从句
as 引导的让步状语从句以部分倒装的形式出现，从句中的表语、状语或谓语部分的实义动词要前置到句首。若作表语的名词前有冠词，则须去掉冠词。如：
Tired as we were，we didn’t give up.（形容词作表语置于句首）
Try as he may，he couldn’t open the door. （谓语部分实义动词try置于句首）
例3 ________，she was able to stand on her own feet.
A. Though a child she was
B. As she was a child
C. A child as she was
D. Child though she was
解析：as 引导让步状语从句，须把作表语的名词提前，且要省掉冠词，as 的这种用法也适用于though，所以选D。
例4 ________，I can’t buy it，for it is too expensive for a student.
A. Much as I like it B. As I like it very much
C. As I like it D. I like it though
解析：根据题意，横线部分意为“尽管我很喜欢它”， as 引导让步状语从句，much为副词，作状语要前置，因此选A。
4.比较状语从句
as在比较状语从句中通常与另一个as连用，构成句型“as...as...”，意为“和……一样”，表示同级比较。使用时[提供/论文和论文/服务，/]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 interesting as that one（is）.
其否定式为“not as/so /adj./ adv. /as”。如：
This dictionary is not as/so useful as you think.
若有修饰成分，如twice，three times，half，a quarter等，则须置于第一个as之前。如：
Your bag is twice as expensive as mine（is）.
例5 I found that homework was not ________ what I used to have in my old school.
A. so heavily as B. such heavy as
C. though heavily as D. as heavy as
解析：同级比较结构为“as/so/形容词或副词原级/as”，此处修饰homework，要用形容词，因此选D。
例6 Five years ago the population of their city was ________ of ours.
A. twice more than those B. as twice large as those
C. twice as much as that D. twice as large as that
解析：根据倍数表达公式，选择D项。
5.方式状语从句
as引导方式状语从句位于主句之后。如：
Always do to the others as you would be done by.
例7 Do ________ you are told to，or you will be fired.
A. like B. as C. so D. such
解析：略论句子可知，第一个分句意为“按照告诉你的去做”，为方式状语从句，答案为B。like 为介词，不能引导句子，so后要接形容词或者副词，such后要接名词。
二、定语从句中的as
as引导限制性定语从句，一般与the same 或 such/so/as连用，指代前面的先行词，在从句中充当主语、宾语或表语。
He is such an honest person as is respected by all of us.（作主语）
The lady wore the same dress as I bought yesterday.（作宾语）
as 引导非限制性定语从句，指代整个主句，位置比较灵活，可位于主句前，也可位于主句后，还可位于主句中间。
She is a fine singer，as her mother used to be.（作表语）
例8 This is so difficult a problem ________ nobody can solve.
A. that B. which C. where D. as
解析：[提供/论文和论文/服务，/]此题同学们容易误选A。problem后面的句子缺少宾语，可判断为定语从句。在定语从句中，当先行词由 such/so/as/the same修饰时，定语从句用as引导，因此选D。
例9 ________，the old lady injured in the traffic accident was in hospital.
A. It was reported B. Which was reported
C. As was reported D. That was reported
解析：考点为as引导非限制性定语从句，联系代词as 指代后面整个主句，所以选择C项。若选which则须将主从句的顺序互换。A项后要加上that，去掉逗号后，构成句式“It was reported that...”。
三、并列句中的as
如果并列句表示“也是如此”之意，可用“as/be/助动词/情态动词”。如：
Her mother is tall and as is she.
例10 I often go to school by bike；________ do my classmates living near our school.
A. as B. such C. who D. which
解析：略论句子可知，分号后的句子为部分倒装结构，答案为A。as在这里相当于so。
（作者单位：湖南石门县一中）
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1.《as的用法归纳》
as的词性较多，可作连词、联系代词、介词和副词，用法也较复杂，英语论文范文，因此同学们掌握该词会对英语学习很有帮助。
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2.《辨析as to与as for》
as to与as for都有“至于”的意思，as for后面通常接名词或动名词，as to后面可接动名词、名词性从句或“疑问词/不定式”。 | 
