as/which引導(dǎo)定語(yǔ)從句的區(qū)別

　　(1)位置不同：as可置于句首，也可置于句中，而which只能放在句中。

　　(2)指代不同。 as引導(dǎo)定語(yǔ)從句時(shí)，其先行詞為整個(gè)主句。which引導(dǎo)非限制性定語(yǔ)從句，其先行詞也可以是主句或主句中的一部分。

　　(3)與主動(dòng)動(dòng)作先后不同：as從句表示的行為經(jīng)常是在主句行為之前，而which引導(dǎo)的定語(yǔ)從句表示的卻在主句之后，表示連續(xù)發(fā)生的事情或結(jié)果等。

　　As was expected, the England team won the football match.

　　He promised to help me, which he did.

　　He was often late for work, which cost him his job.

　　注意先行詞為時(shí)間、地點(diǎn)或原因時(shí)，關(guān)系詞的選用

　　如果用when, where 或why，關(guān)系詞在從句中應(yīng)該是做狀語(yǔ),否則的話則應(yīng)該用which / that等。例如：

　　I will never forget the days ________ I spent with my friends in the country.

　　that/which/ \

　　exercises

　　1. The boy was paid $10 for washing ten windows, most of ____ hadn’t been cleaned for at least a year. (2005/10)

　　A.those B.these

　　C.that D.Which

　　2. Anyone ______ has something interesting to concentrate on won't find life boring. (2005/4)

　　A. whoever B. whomever

　　C. who D. which

　　D C

　　3. Athletes ______ at the Olympic Games are supposed to be nonprofessionals. (2004/10)

　　A. who compete B. who are competing

　　C. who will compete D. who have competed

　　4. Television, ______ came into being in 1939, did not become common until the early 1950s. (2004/4)

　　A. that B. what

　　C. which D. it

　　A C

　　Adverbial Clauses

　　用作狀語(yǔ)的從句叫狀語(yǔ)從句(adverbial clause).