近幾年大學聯考試卷中有關as一詞的題目出現過很多次，其中as或是最佳選項，接下來要給大家分享的是定語從句as的用法，歡迎大家的借鑑閱讀！
定語從句as的用法
一、用作連詞的as
1. 引導時間狀語從句，表示“當……的時候”，其用法與when和while類似。例如：As a child (When he was a child), she was sent to six different schools.此用法中as多表示從句與主句動作同時進行，意為“一邊……一邊……”，一般不與狀態動詞連用。例如：She sang songs as she did her homework.
as 還可以表示一動作緊接著另一動作發生，說明另一動作的結果，有“隨著……”的.含義。例如：As time went by, we found he was an honest man./As he grew older, he lost interest in everything except gardening.
例1 It wasn’t until nearly a month later________ I received the manager’s reply.
A. since B. when C. as D. that
解析：本題的as中與when一起作為干擾項，容易使考生往時間狀語從句上思考，事實上本題是強調句，正確選項是D。
2. 引導原因狀語從句，表示“由於，因為”，相當於because, 但通常置於句首。例如： As he is a qualified doctor, I trust his advice on medical matters.
例2 _____ modeling business is by no means easy to get into, the good model will always be in demand.
A. While B. Since C. As D. If
解析：本題中as干擾性很強，很多考生誤以為是原因狀語從句，但仔細分析不難發現正確答案應是A(while表示“只要”)。
3. 引導讓步狀語從句，通常可與although或though通用，但語序不同，although或though用於句首，as用於倒裝結構。例如：Young as I am, I already know what career I want to follow. /Although(或Though)I am young, I already know what career I want to follow. as 表示讓步用於倒裝結構，通常將從句的表語、狀語或動詞前置。如果表語有冠詞a/an, 需去掉。例如：Great scholar as he is, he is lacking in common sense./Much as I like you, I couldn’t live with you. 例3 _____ he has limited technical knowledge, the older worker has a lot of experience.
A. SinceB. Unless C. As D. Although
解析：as 雖然有引導讓步狀語從句用法，但本題不是倒裝結構，故正確答案應是D。
4. 引導方式狀語從句，表示“如，像”。例如：When in Rome, do as Romans do./Do to others as you would have others do to you.
例4 We wanted to get home before dark, but it didn’t quite ________ as planned.
A. make outB. turn out C. go onD. come up
解析：本題考查動詞片語辨析，題幹中的“as planned”給同學們提供了重要資訊，答案選B。
5. 固定句型：“主句，as +be/do+主語”表示“也一樣”。例如：She’s unusually tall, as are both her parents./He’s a doctor, as was his wife before she had children.
二、用作介詞的as
1.表示“如，像”。例如：They got united as one man./She spoke of me as her dearest friend.
2.表示“作為、當作”。例如：As a League member, you should think more of others.
3.與某些動詞搭配，表示“把……當作……”，如：look on…as…, regard…as…, treat…as…, consider…as…, think of…as…, see…as…等。其中consider…as…中的as可以省略。as與famous或known搭配，表示“作為……而出名”。
例5 Linda worked for the Minnesota Manufacturing and Mining Company, ________ as 3M.
A. knowingB. known C. being knownD. to be known
解析：如果熟悉be known as這一短語，運用有關非謂語動詞的常識，可選出正確答案B。
三、用作關係代詞的as
1. 引導限制性定語從句，先行詞前通常有as, so, such, same等修飾語。例如：He will marry as pretty a girl as he can find./My hometown is no longer the same as it used to be./As many people as are present will be given a present.在此種用法中，同學們要注意與結果狀語從句的區別。比如：A: The teacher asked us such a difficult question that none of us could answer it. B: The teacher asked us such a difficult question as none of us could answer.A句為結果狀語從句，而B句則是定語從句。
2. 引導非限制性定語從句，用來指代整個主句(即先行句)，表示“這一事實，那一情況”。從句可以位於句首、句中或句末。例如：We stand when the national anthem is played, as is the custom.
例6 ______ I explained on the telephone, your request will be considered at the next meeting.
A. When B. After C. As D. Since
解析：根據句意，選項C是正確答案。as表現的正是本點所講用法。
四、用作副詞的as
修飾形容詞或副詞，表示程度，意為“同樣地”。例如：He swims fast, but I swim just as fast. 但它通常構成表示比較的結構“asas”，“not asas”。此結構中第一個as是副詞，第二個as是連詞。否定結構中的副詞as可以由so代替。asas possible /one can也屬於此用法。例如：It is generally believed that teaching is as much an art as it is a science.
五、用在習語中的as
由as構成的習語很多，常見的有：as soon as “一就”，引導時間狀語從句;as/so long as “只要”引導條件狀語從句;as if/though “好像，彷彿”，引導方式狀語從句或表語從句;as to/ as for “至於，就而言”;as much/many as“多達”;as/so far as “就的限度”;as a result，as a result of “(由於的)結果”;as a matter of fact“事實上”;as well “也、還”;A as well as B“不但A而且B”;as it is“照現狀看，看樣子”，等等。這些習語在大學聯考中可能經常遇到，在大學聯考題中有的作為正確選項，有的作為干擾項，有的出現在題幹，值得同學們認真掌握。例如：
例9 I would like a job which pays more, but ______ I enjoy the work I’m doing at the moment.
A. in other wordsB. on the other hand C. for one thing D. as a matter of fact 解析：選項D極具干擾意義，但進一步研讀會發現本題中的兩個分句表達了一件事的兩個對立面，故選B。
例10 ——People should stop using their cars and start using public transport. ——______. The roads are too crowded as it is.
A. All right B. Exactly C. Go aheadD. Fine
解析：本題選項中雖沒有as內容，但題幹中的as it is卻是解題的關鍵資訊，正確選項為B。
