在高三課本第十五單元出現(xiàn)了下面幾個句子：
1 As Kofi Anna，Secretary General of the United States said，“each contribution -- how small -- can help make a difference.”
2 Now she is spending a year in remote part of southwest China working as a volunteer teacher in a village school.
這幾個句子都涉及到了as的用法。作介詞用，第一句話中as用作關(guān)系代詞，引導定語從句，含義為“正如”，第二句話中as的含義為“作為，當作”，做介詞。
下面讓我們結(jié)合歷年高考試題對其用法進行分析。
一.用作連詞引導讓步狀語從句
從句必須用倒裝語序，把作表語用的名詞(不加冠詞)或作表語的形容詞，或動詞(原形)，或副詞提到as前面。如：
1.Child as he is，he knows a lot.
2.Tired as they were，they stayed up late preparing for the coming exams.
3.Try as he would，he failed again this time.
考例：1.(2005重慶)___，he talks a lot about his favorite singers after class.
A.A quiet student as he may be
B.Quiet student as he may be
C.Be a quiet student as he may be
D.Quiet as he may be a student
【解析】答案是B。作表語的是名詞student，名詞前不加冠詞。
2.(2005.廣東)____，Carolina，couldn’t get the door open.
A.Try as she might B.As she might be C.She might as try D.Might she as try
【解析】答案是A。as引導讓步狀語，將動詞原形try提到as前面。
二.用作關(guān)系代詞，引導定語從句
as用作關(guān)系代詞，引導定語從句，含義為“正如”。如：
1.He is very careful，as his work shows.
2.As is known is reported in the newspaper，talks between the two countries are making progress.
考例：(2005浙江)___I explained on the phone，your re quest will be considered at the next morning.
A.When B.After C.As D.Since
【解析】答案是C。意思是“正如我在電話里解釋的那樣……”。
2.(2006)The Beatles，____many of you are old enough to remember，came from Liverpool.
A.what B.that C.how D.as
【解析】答案是D。引導非限制性定語從句。
三.作為副詞
用于表示“和……一樣，”的意思，as…as中間要用形容詞/副詞的原級，如as long as：長達;as far as遠達;as much as：多達;as tall as含義為“高達…”。如：
That day they walked as far as ten kilometers in two hours.
考例：(2005安徽)John is the tallest boy in the class，_______according to himself.
A.five foot eight as tall as B.as tall as five foot eight C.as five foot eight tall as D.as tall five foot eight as
【解析】選B.as…as中間要用形容詞/副詞的原級。
四.引導時間狀語從句
含義為“當…的時候”，如：
1.I watched her as she combed her hair.
2.As he grew older ，he lost interest in everything except gardening.
考例：1.(NMET1994)Mother was worried because little Alice was ill，especially____Father was away in France.
A.as B.that C.during D.if
【解析】答案是A.“在……時候”，相當于when.而C選項是介詞，不接句子。
2.(MET90)_____the day went on，the weather got worse.
A.With B.Since C.While D.As
【解析】答案是D.“隨著”的意思，as the day went on可以作為固定結(jié)構(gòu)記住。
五.作介詞用
有“作為，當作”的意思。如：
1.They were all dressed as clowns.他們都打扮得如小丑。
考例：(2005廣東)I feel that one of my main duties_____a teacher is to help the students to become better learners.
A.for B.by C.as D.with
【解析】選C。“作為教師”的意思。
