彭　英

1.unless引導(dǎo)條件狀語從句

【課文原句】You should not go rafting unless you know how to swim，and you should always wear a life jacket.

【經(jīng)典考例】We wont keep winning

games________we keep playing well.(NMET 2006 浙江卷 )

A.because B.unlessC.when D.while

【考點(diǎn)解析】句意“除非我們繼續(xù)打好比賽，否則我們就不能連續(xù)獲勝?！?because意為“因?yàn)椤保龑?dǎo)原因狀語從句；unless意為“除非；如果不”，引導(dǎo)條件狀語從句；when意為“當(dāng)……時候”，引導(dǎo)時間狀語從句；while表示“在……期間；雖然”，可引導(dǎo)時間、讓步狀語從句或并列句。答案為B。

2.as well as連接比較狀語從句

【課文原句】Eco-travel is a way to find out what can be done to help animals and plants as well as people.

【經(jīng)典考例】John plays football________ ，if not better than.David.

A.as well B.as well as

C.so well D.so well as

【考點(diǎn)解析】句意：“約翰如果踢足球不比大衛(wèi)踢得更好，也至少與他踢得一樣好?！盿s well as 在課本這個句子中是連詞，意為“以及”，是個固定整體而在考例中的as well as 只有后一個as是連詞，意為“像”，“同”，第一個as 是副詞，意為“一樣”，修飾well，所以不是一個固定整體?？梢园淳湟獠煌f as bad as，as early as ，as clever as 等，不能混為一談?？祭械腶s well as，意為“同……一樣好”。題中的if not better than是插入語，省去后不難看出試題變成了同級比較結(jié)構(gòu)“John plays football as well as David”。答案為B。

as well as作“以及”解用來連接兩個并列的名詞或代詞。它強(qiáng)調(diào)的是前一項(xiàng)，后一項(xiàng)只是順便提及，not only…but also側(cè)重后者，也就是說A as well as B= not only B but also A。例如：

Mr.Brown has experience as well as knowledge.布朗先生不僅有知識而且有經(jīng)驗(yàn)。(側(cè)重前者，即experience)(=Mr Brown has not only knowledge but also experience.)(著重后者，即but also后面的部分)

as well as連接并列主語時，動詞須和as well as前面的主語在數(shù)上取得一致；not only…but also連接句子中的并列成分時，動詞的數(shù)則和but also后面的主語取得一致。例如：

The pilot as well as two of the passen-gers has escaped death.(as well as前的主語pilot是單數(shù)，故動詞用has。)

Not only two of the passengers but also the pilot has escaped death.(but ɑlso后的主語the pilot是單數(shù)，故動詞用has。)

3.before引導(dǎo)時間狀語從句

【課文原句】However，before she could think twice，the water was upon her.

【經(jīng)典考例】

—Why didnt you tell him about the meeting?

—He rushed out of the room________I could say a word.(NMET 2006 四川卷)

A.beforeB.until

C.whenD.after

【考點(diǎn)解析】句意“你為什么沒告訴他這次會議的情況?”“我還沒來得及說，他就從房間里沖了出去。”before引導(dǎo)時間狀語從句，表示“在……之前；還沒來得及”，強(qiáng)調(diào)從句動作發(fā)生之前，主句動作已發(fā)生。答案為A。

注意before其它的用法：

1.表示“在……之后……才”。

The American Civil War lasted four years________the North won in the end.(NMET 2005廣東卷)

A.after B.before C.when D.then

【解析】：答案為B。本題考查連詞before表示“在……之后才……”之的用法，根據(jù)本句含義“美國南北戰(zhàn)爭持續(xù)了四年，北方才最終取得勝利"，可知本題應(yīng)選B。

2.表示“在……之前就……”。這時主句與before從句中的兩個動作按時間先后依次發(fā)生。

It was evening________we reached the little town of Winchester.(NMET 2004天津卷)

A.that B.until C.since D.before

【解析】：答案為D。本題考查連詞before表示“在……之前就……”的用法。句意是“我們到達(dá)小鎮(zhèn)Winchester之前就已經(jīng)是傍晚時分了”。

3.表示“趁……”，“等到……”，或 “沒等……就…… ”等。

He made a mistake，but then he corrected the situation________it got worse.(NMET 2003北京卷)

A.until B.when C.before D.as

【解析】：答案為C。由made a mistake和轉(zhuǎn)折詞but可知本題句意是“他出了差錯，但沒等其進(jìn)一步惡化，他就改正了”。故正確答案為C。

4.用于句型“It + will/would be + 時間段 + before...”句型中，表示“要過多久才…”，其否定形式“It will/would not be +時間段+ before…”表示“不久就……，過不了多久就……”。

The field research will take Joan and Paul about five months；it will be a long time________ we meet them again.(NMET 2007安徽卷)

A.after B.before C.since D.when

【解析】：答案為B。before 用于肯定的“It + will be + 時間段 + before...”句型中，表示“要過多久…才…”。

4.動詞-ing形式作伴隨狀語

【課文原句】“Run!” Jeff shouted，seizing her arm.

【經(jīng)典考例】“You cant catch me!”

Janet shouted，________away.(NMET 2005 全國卷II)

A.runB.running

C.to runD.ran

【考點(diǎn)解析】句意：“‘你抓不住我的!珍妮特邊喊邊跑?！庇删渲械亩禾柨芍?，shout后不是并列的謂語動詞，而是表伴隨的狀語，由于run和主語Janet是主動關(guān)系，故用動詞-ing形式。一般來說動詞-ing形式作伴隨狀語，它所表達(dá)的動作或狀態(tài)是伴隨著句子謂語動詞的動作而發(fā)生或存在的。答案為B。5.must have done表推測

【課文原句】Tree after tree went down，cut down by the water，which must have been three meters deep.

【經(jīng)典考例】

—Tom is never late for work.Why is he________ absent today?

— Something________to him.________ (NMET 2005江西卷)

A.must happen

B.should have happened

C.could have happened

D.must have happened

【考點(diǎn)解析】句意“湯姆上班從不遲到。今天他為什么沒來?”“他一定是出了什么事情。” 答案為D。must have done表對過去所發(fā)生事情 的肯定性推測，如果是否定性的推測，要用cant /couldnt have done。

注意對must have done進(jìn)行反問疑問時，反意疑問句應(yīng)為對過去發(fā)生的那個動作的時間提問，應(yīng)特別注意句子中的時間狀語。試比較：

You must have been to Beijing several times，havent you? 你肯定到北京去過好幾次了，是嗎?

Li Tao must have given up smoking three years ago，didnt he? 李濤一定是三年前戒了煙的，是嗎?

Smith must have got to London by now，hasnt he? 史密斯現(xiàn)在肯定已經(jīng)到了倫敦，是嗎?★