、摘要:结构型虚拟语气
??从近年考题来看，语法结构题型较为分散，涉及了大学英语阶段必须掌握的所有语法知识和常用句型。但通过对历年大学英语四级考试语法题的分析，可发现语法考试的重点突出表现在虚拟语气、非谓语动词、从句、情态动词、倒装句、时态等几个方面，尤其是以上项目的特殊用法。?
??(1)虚拟语气?
??四级考试对虚拟语气的考查重点在四个方面：A.结构型虚拟语气;B.虚拟语气的倒装结构;C.含蓄虚拟条件句; D. 混合型虚拟条件句。?
A. 结构型虚拟语气?
??顾名思义，此类虚拟语气与特殊结构有关，例如
??It is (about / high) time + that从句(从句谓语动词用一般过去时);
??would rather/just as soon + that从句(从句谓语动词用一般过去时);
??lest (或for fear / in case) + that从句(从句谓语动词用should + 动词原形，should 可以省略);
??It is vital / necessary / important / urgent / imperative/ desirable / advisable / natural / essential + that从句(从句谓语动词用should + 动词原形，should 可以省略);
??It is suggested / ordered/ demanded / required等表示建议、命令等意义的过去分词 + that从句(从句谓语动词用should + 动词原形，should 可以省略);
??suggest, propose, recommend, insist等表示坚持、建议、命令、要求的词，后面的宾语从句的谓语动词用should + 动词原形，should 可以省略;??suggestion, proposal, advice等表示坚持、建议、命令、要求的名词，后面的同位语从句的谓语动词
用should + 动词原形，should 可以省略。
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??例：I don't think it advisable that Tim ______to the job since he has no experience.?
??A. is assigned ??B. will be assigned ?
??C. be assigned???D. has been assigned(June, 1997)?
??答案B。参考译文：既然蒂姆没有经验，我认为把这项工作交给他是不明智的。
??B. 虚拟语气的倒装结构?
??虚拟条件从句中的谓语动词如果与were或should，had等词连用时，可以省略连词if将were,should，had移至句首形成倒装。?
??例： ______before we depart the day after tomorrow, we should have a wonderful dinner party.?
??A. Had they arrived ?B. Would they arrive?
??C. Were they arriving D. Were they to arrive (January, 1997)?
??答案D。参考译文：如果他们能在后天我们离开之前到，我们将举行一场丰盛的晚餐聚会。
??虚拟语气在表示与将来事实相反，或实现可能性不大的假设时，从句的谓语动词用过去式，were + 不定式，或should + 动词原形，此处将if 省略，were前置。
??C. 含蓄虚拟条件句?
???这种虚拟条件句中没有明显的虚拟条件，而是利用其它词汇手段加以暗示。常用于此功能的词汇有：otherwise，but for，with，without，if only等。?
??例：If only the committee _____the regulations and put them into effect as soon as possible.?
??A. approve??????B. will approve ?
??C. can approve????D. would approve(January, 1997)?
??答案D。参考译文：要是委员会能通过这项法案并尽可能付诸实施就好了!If only 后连接一个从句，单独使用表示"要是...就好了)?，从句要用虚拟语气。
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??D. 混合型虚拟条件句?
??混合型虚拟条件句虽较少出现，但也是虚拟语气的特殊形式，故应稍加注意。?
??例：If I hadn't stood under the ladder to catch you when you fell, you_____ now.?
??A. couldn't have smiledB. wouldn't be smiling?
??C. didn't smileD. won't smile(January, 1999)?
??答案B。参考译文：如果你摔下来时我不站在梯子下接住你，你现在就不会笑了。从句表示与过去事实相反， 主句由于有时间状语 "now" 表示与现在事实相反,所以选项B为正确答案。?
??(2)非谓语动词?
??非谓语动词为四级考试出题最多的题型之一，重点考查不定式、分词和动名词的句法功能，以及独立结构的句法功能。
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??A. 不定式和分词?
??在英语中非谓语的形式主要为不定式和分词，其中不定式表示目的、未来的动作，现在分词表示正在进行的或主动的动作;过去分词表示已经完成的或被动的动作。注意，不定式还可以用作名词或名词词组的定语，被修饰的名词或名词词组属于不定式的同位结构，不定式用主动语态，例如：The boy had an impulse to jump over the fence. 如果不定式属于不及物动词，或由于意义和结构上的需要，后面就得加介词，例如：At least there's something to write home about.?
例：The pressure_____ causes Americans to be energetic, but it also puts them under a constant emotional strain.(January, 1998)?
??A. to compete????B. competing?
??C. to be competed??D. having competed?
??答案A。参考译文：竞争的压力使美国人精力充沛，但也使美国人一直处于紧张的状态之下。此处不定式修饰名词，名词属于不定式的同位结构，所以用主动语态，故选项A为正确答案。?
??B. 动词原形或分词作宾语或宾补
?? 英语中有些动词或短语后要接动词原形作宾语或宾补，这类动词和短语有：feel, have, hear, let, listen to, look at, make, notice, observe, see, watch, cannot but, do nothing but, had better, would rather... than..., had best等。注意:hear, listen to , look at, notice, observe, see, watch后既可以接动词原形作宾补，也可以接动词的现在分词或过去分词作宾补;接动词原形时表示此动作已经发生，接动词的现在分词则表示此动词正在进行之中，接动词的过去分词则表示此动作是被动的。
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??例：You will see this product wherever you go.?
??A. to be advised?? ?B. advertised?
??C. advertise???D. advertising(June, 2000) ?
??答案B。参考译文：你无论走到哪里，都会看到这个产品的广告。see后面所接的宾语补足语可以是动词原形、现在分词或过去分词，此处产品是被做广告，因此要用过去分词，故选项B为正确答案。
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??C. 动名词作宾语?
??英语中有些动词或短语后要接动名词作宾语，这类动词和短语有：acknowledge, admit (to), advise, advocate, anticipate, appreciate, avoid, consider, delay, deny, endure, enjoy, escape, fancy, finish, imagine, involve, justify, mind, miss, permit,postpone, practice, prevent, require, resist, risk, suggest, understand, be opposed to, can't help, confess to, feel like, have difficult/trouble (in), look for
??ward to, object to, submit to, be busy, be worth, It is no use/good ...等。
有些动词后既可以接动名词作宾语也可以接不定式作宾语，但含义不一样。例如：forget to do something忘记要去做某事; forget having done something忘记做过了某事; mean to do something打算做某事; mean doing something意味着……; remember to do something记得要去做某事;
remember having done something记得做过某事; regret to do something遗憾要去做某事(regret后跟不定式作宾语只限于少数动词，如inform, say, tell, report等); regret having done something后悔做过某事; stop to do something停下来去做某事; stop doing something停止做某事; try to do something尽力去做某事; try doing something尝试着做某事; want to do something想要去做某事;want doing需要进行……?
??例：The man in the corner confessed to a lie to the manager of the company.?
??A. have told? B. be told?
??C. being told??D. having told(June, 1997)?
??答案D。参考译文：角落的那个人供认对公司的经理说了谎。confess to 后接动名词，此处 动名词的动作先于谓语动词，所以要用动名词的完成时态，故选项D为正确答案。
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??D. 独立主格分词作状语时，要特别注意其逻辑主语和主句的主语一致。
否则，分词必须有自己的主语，构成独立主格。?
??例：______, a man who expresses himself effectively is sure to succeed more rapidly than a man whose command of language is poor.?
??A. Other things being equal
??B. To be equal to other things?
??C. Were other things equal
??D. Other things to be equal(June, 1997)?
??答案A。参考译文：在其他条件相同的情况下，一个善于表达自己的人要比一个不善言谈的人较快地获得成功。此处be equal的主语明显不是we, 所以必须用独立主格形式，故选项A为正确答案。?