四级语法考察重点

 　　英语是一个重结构的语言，要求句子必须符合句法结构的要求。用来规定句法结构的一些原则也就是我们常说的语法。英语中的语法条文比较多，总的来说可分为两大类，即词法和句法。具体说来，有情态动词的用法，形容词和副词的比较级用法，非谓语动词的用法，时态和语态，定语从句，状语从句，虚拟语气，名词性从句，倒装，强调与并列，主谓一致等。经过统计，95年1月到2000年6月，仅词汇和句法部分对语法的考查就有190题，占52.8%，其中以非谓语动词、虚拟语气、时态/语态、状语从句和定语从句考查最多。今天这一讲我们重点讲时态/语态、虚拟语气和各种从句，下一讲重点讲非谓语动词等。

　　一、时态和语态
　　英语中共有16个时态，最常用的是一般现在时、一般过去时、一般将来时、现在和过去进行时、现在完成时、过去完成时。但从95年以来的考题统计来看，15个时态考题中将来完成最多，占3题，时态考查的次序依次为将来完成时--- 过去完成时 --- 现在完成进行时 --- 现在完成时 --- 一般将来 --- 一般过去。先看以下各题：
　　Test Yourself:
　　-----------------------------------------------
　　1) My train arrives in New York at eight o'clock tonight. The plane I would like to take from there ___ by then.(1999.1)
　　A. would leave 　　B. will have left 　　C. has left 　　D. had left
　　2) She ought to stop work; she has a headache because she ____ too long.(2000.1)
　　A. has been reading 　　B. had read 　　C. is reading 　　D. read
　　3) "May I speak to your manager Mr. Williams at five o'clock tonight?"(2000.6)
　　"I'm sorry. Mr. Williams ____ to a conference long before then."
　　A. will have gone 　　B. had gone 　　C. would have gone 　　D. has gone
　　4) Great as Newton was, many of his ideas _____today and are being modified 1 by the work of scientists of our time.(1997.1)
　　A. are to challenge 　　B. may be challenged 　　C. have been challenged 　　D. are challenged
　　5) Before the first non-stop flight made in 1949, it ____ necessary for all planes to land for refueling. (1996.6)
　　A. would be 　　B. has been 　　C. had been 　　D. would have been
　　6) He came back late, ____ which time all the guest had already left.(1999.6)
　　A. after 　　B. by 　　C. at 　　D. during
　　7) Until then, his family ______from him for six months. (1997.1)
　　A. didn't hear 　　B. hasn't been hearing 　　C. hasn't heard 　　D. hadn't heard
　　Explanation and Expansion 2
　　-----------------------------------------------
　　A：参考答案：1）B 2）A 3）A 4）C 5）C 6）B 7）D
　　B：评析：
　　1) 以上各题都与完成时有关，完成时态用来表示到某一个时间为止已经完成的动作或某个状态/动作一直持续到某个时间。如果时间为过去，则用过去完成时，即表示过去的过去，如5）和7）。
　　2) 如果表示到将来某个时间为止已经完成的动作，则用将来完成时，如1）和3），再如：
　　It's reported that by the end of the month the output 3 of cement 4 in the factory ____ about 10%.
　　A. will have risen B. has risen
　　C. will be rising D. has been rising
　　3) 而现在完成时表示到目前为止某个动作已经结束，对现在有影响，如4）。从下文中的"正在修改"可以判断人们已经对牛顿的观点提出挑战，而不是将要提出挑战或者可能提出挑战，由此可以判断应该用现在完成时。
　　4) 与现在完成时不同，现在完成进行时则表示某个动作从过去持续到现在，并且仍在进行，如2）。头疼的原因是看书时间太长。本题可以用现在完成时，但不会是过去完成时，选项B不对，一般现在时表示经常发生的动作，与这里的头疼不能构成直接的因果关系，由于时间状语表示的是一段时间，有不可能是现在进行时，所以这里只能用现在完成进行时。
　　C．完成时态使用注意事项
　　① 完成时的时间状语一般表示"到……为止"，以"by"短语居多。如果句中的时间状语是由by引出的短语或从句，谓语动词一般是用完成时态，如：
　　By the time we got there, the fire had already been put out.
　　We'll have completed the task by the time you come back.
　　② 在完成时态中，终止性动词不能与表示一段时间的时间状语连用，而表示状态或动作持续的谓语动词必须与表示一段时间的状语连用。
　　The conference ____ a full week by the time it ends
　　A. must have lasted
　　B. will have lasted
　　C. would last
　　D. has lasted (1997.1)
　　It seems oil ___ form this pipe for some time. We'll have to take the machine apart to put it right.
　　A. had leaked
　　B. is leaking
　　C. leaked
　　D. has been leaking (1997.6)
　　这两题中都有表示动作持续的一段时间，应该用完成时态。
　　但是，如果只表示状态已经存在，则不能用完成时态，如：
　　By then, he knew what he waned 5 to be when he grew up.
　　③ 完成时可以用来表示量的积累。
　　④ 对于完成时的考查有两种，一种是时态本身的选择，另一种是根据时态选择时间状语，如6）。从句时态为过去完成时，表示等到他回来，客人都已经离开了，与完成时态连用的，表示"到……为止"的应该是介词by。
　　Pactise Yourself
　　-----------------------------------------------
　　下面请同学们做《语法分册》第五章 二至四节相关题目。然后对照评析自检。
　　Test Yourself
　　刚才我们看了完成时态的考查，现在我们一块来看以下其它时态，请先试做以下各题：
　　1) Turn on the television or open a magazine and you _____ advertisements showing happy, balanced families.
　　A. are often seeing 　　B. often see 　　C. will often see 　　D. have often seen (1995.6)
　　2) While people may refer to television for up-to-the-minute news, it is unlikely 6 that television _____ the newspaper completely.
　　A. replaced 　　B. have replaced 　　C. replace 　　D. will replace (1995.6)
　　3) I'm sorry I can't see you immediately; but if you'd like to take a seat, I'll be with you ____.
　　A. for a moment 　　B. in a moment 　　C. for the moment 　　D. at the moment (1999.1)
　　4) If she doesn't tell him the truth now, he'll simply keep on asking her until she _____.
　　A. does 　　B. has done 　　C. will do 　　D. would do (1998.6)
　　Explanation and Expansion
　　A. 参考答案： 1）C 2） D 3） B 4） A
　　B. 评析
　　从以上各题可以看到，在解时态考题时应注意一下几点：
　　① 结合形容词选择时态，如2）。从unlikely一词可以看出从句表示的是将来不大可能发生的事情，自然用一般将来时。类似的形容词还有possible, probable 7, impossible等。
　　② 根据时态判断时间状语。如3）。谓语动词为将来时态，说明时间应该是in a moment，表示我一会就去见你。for a moment同样可以与将来时态连用，但表示的是"与某人一块待一小会"，这样就与上文的I can't see you immediately意思上冲突。
　　③ 注意句型对时态的要求，如1）。该句型中祈使句表示一种条件，第二个分句中一般要用will表示在这种条件下可能发生的事情。但是，本题中often的使用可能会造成一定的迷惑。这就要求考生对各种时态的表达方式，以及其作用了解清楚。Will可以表示习惯。
　　④ 注意时间、条件和让步状语从句中时态的运用。
　　一般在时间、条件和让步状语从句中用一般现在时表示一般将来
　　，用一般过去时表示过去将来，用现在完成时表示将来完成，用过去完成时表示过去将来完成。如4）。在如：
　　He promised to send me an email as soon as he got there.
　　No one is to leave the room until he has done the task.
　　但注意特殊句型中的时态，如：
　　hardly/scarcely …when…
　　no sooner… than…
　　Hardly had I put down the receiver when the telephone rang again.
　　No sooner had they got to know the news than they went to the bar to enjoy a drink.
　　Self-practice
　　请同学们做《语法分册》第五章 第六节进行自我训练。
　　Test Yourself
　　刚才我们一起分析了时态的考查特点和答题时应该注意的事项，现在我们一起来看一下语态的考查。语态的考查一般都与时态的考查相结合。在解语态题的同时必须考虑时态的因素。请同学们先做以下下列各题：
　　1) The last half of the nineteenth century ____ the steady improvement 8 in the means of travel.(1998.6)
　　A. has witnessed 　　B. was witnessed 　　C. witnessed 　　D. is witnessed
　　2) The grey building is where the workers live, and the white one is where the spare parts ____.(19995.1)
　　A. are producing 　　B. are produced 　　C. produced 　　D. being produced
　　3) This kind of glasses manufactured 9 by experienced 10 craftsmen 11 ____ comfortably.
　　A. is worn 　　B. wears 　　C. wearing 　　D. are worn (2000.1)
　　4) The fifth generation computers, with artificial 12 intelligence, ____ and perfected now.(1996.1)
　　A. developed 　　B. have developed 　　C. are being developed 　　D. will have been developed
　　5) Sir Denis, who is 78, has made it that much of his collection ____ to the nation.(1996.6)
　　A. has left 　　B. is to leave 　　C. leaves 　　D. is to be left
　　6) As teachers we should concern ourselves with what is said, not what we think ____.(1997.6)
　　A. ought to be said 　　B. must say 　　C. have to be said 　　D. need to say
　　7) Once environment damage ____, it takes many years for the system to recover.(1997.6)
　　A. has done 　　B. is to do 　　C. does 　　D. is done
　　Explanation and Expansion
　　A. 参考答案：1）C 2） B 3） B 4） C 5） D 6） A 7）D
　　B. 评析
　　① 是否可用被动语态主要看谓语动词与句子主语之间的关系，如果是动宾关系自然用被动语态。
　　② 注意被动语态的各种时态构成，但四级考试中没有正误结构的判断，考生只需要根据上下文判断出该用什么时态即可。
　　③ 不及物动词不可能有被动语态，但及物动词也未必有被动语态，主要是看句子侧重表达的概念，如3题中wear表示眼镜的特点，不可用被动语态。在如：
　　This kind of software sells well.
　　It being too cold, the car wouldn't start.
　　won't wouldn't表示"拒绝"谓语动词不用被动形式。
　　④ 注意含有情态动词的被动语态的结构，以及类似的结构，如have to be done, used to be done, be said to be done, be to be done。把握各种结构表示的意思。然后就是根据具体的上下文选择适当的情态动词或时态的问题。
　　Self-practice