【编者按】2011年学位外语考试在即，为了帮助大家复习，威廉希尔app 的小编特别整理了学位英语考试英语语法重点复习，供大家参考。
虚拟语气
所表示的条件根本不可能实现或实现的可能性很小，称为虚拟条件句。
虚拟条件句，主句与从句中谓语动词的形式可分为下面三类：
假设类型 条件从句动词的时态 结果主句的动词的时态
与现在事实相反 if + 过去式(be只用were不用was) would/should/might/could + 动词原型
与过去事实相反 if had + 去过分词 would/should/might/could + have + 过去分词
与将来事实可能相反 if were to + 动词原形if should + 动词原形 would/should/might/could + 动词原型
一、在条件句中的应用：
If he had time， he would come. 如果有时间，他一定来。(已经过去)
A. 现在事实
I would certainly go if I had time. 如果我有时间当然去。
If he were here， he might help you. 如果他在这也许帮能你。
1、I would ask George to lend us the money if I _____ him. (C， 95年)
A. had known B. have known C. knew D. know
B. 过去事实
59、If Bob____ with us， he would have had a good time. (C， 95年)
A. would come B. would have come C. had come D. came
C. 将来事实
we would state at home if it should rain tomorrow.
If I were to do the examination I would it some other way.
注意：
⑴条件从句中，如果含有be动词、助动词、情态动词， had， should或动词to have，可省略if，要倒装，即把这些词放到主语前面。
1. _____ you were busy， I wouldn't have bothered you with my questions. (B， 96年)
A. If I realized B. Had I realized C. Did I have realized that D. As I realized
57. Had the weather been good， the children _____ out for a walk. (2001)
A. had gone B. could have gone C. would go D. went
答：B.当虚拟语气中含有were， had， should， would等词时， 可以省略if， 把这些词放在主语之前。Should I meet her， I would tell her.万一我见到他， 我会告诉他的。Were I in your position， I would do it better.如果我处在你的位置上， 我会做的更好。Had they made preparations， they would have succeeded.如果他们准备了的话， 他们应该能成功的。本句为和过去的事实相反的虚拟语气，因此选B.
32. the advice of his friends， he would not have suffered such a heavy loss in his business. (D， 0404)
A. If he took B. If he should take C. Were he to take D. Had he taken
⑵ 条件从句有时可以用介词短语代替。有时一个假设的情况不用条件从句表示，而用其它方式来表示，这样的句子叫含蓄条件句。常用with，without，but for.
We couldn‘t have achieved so much without your help.
要不是你们帮忙我们不会取得这么大的成绩
36. But for my classmates‘ help， I the work in time. (D， 0404)
A. did not finish B. could not finish C. will not finish D. would not have finished
32. Without heat and sunlight， plants on the earth well. (A， 0411)
A. would not grow B. will not grow C. had not grown D. would not be grown
⑵ 条件从句有时可以用介词短语代替。有时一个假设的情况不用条件从句表示，而用其它方式来表示，这样的句子叫含蓄条件句。常用with，without，but for.
We couldn‘t have achieved so much without your help.
要不是你们帮忙我们不会取得这么大的成绩
36. But for my classmates‘ help， I the work in time. (D， 0404)
A. did not finish B. could not finish C. will not finish D. would not have finished
32. Without heat and sunlight， plants on the earth well. (A， 0411)
A. would not grow B. will not grow C. had not grown D. would not be grown
二、以wish(that)引导的表示“愿望”的宾语从句，虚拟语气中时态类似在非真实条件从句中时态的应用—时态后移， 引导从句的that可以省略
⑴表示现在或将来的愿望相反的用过去时：主语+wish +从句(过去时) were
I wish (that) I were as young as you. 我真希望和你们一样年青
I wish (that) I knew his address. 我真希望知道他的地址
与将来的愿望相反即愿望难以实现(用过去将来时)，I wish I could be of more use in the future.我希望我将来有点用处。
⑵表示与过去没有实现的愿望用过去完成时：
主语+wish +从句(主语+过去完成时)
I wished he hadn‘t made the big mistake.他要是不犯那个大错误，该有多好!
32. Peter wishes that he ___ law instead of literature when he was in college.
(C， 2000)
A. could study B. studied C. had studied D. would study
53. I didn‘t go to the party， but I do wish I _____ there. (C， 2001)
A. were B. would be C. had been D. will be
三、以suggest，propose， order， command， demand，require，request， insist， desire， advise， ask等词后引导的宾语从句，从句结构为should+动词原形，should可省略
They requested that the students (should) learn the second language.
他们要求学生要学第二外语。
1、The doctor advised that Mr. Malan ____ an operation right away so as to save his life.
A. had B. would have C. have D. was going to have (C，98年)
58、His mother insisted that he _____ the coat when going out. (A， 99年)
A. put on B. puts on C. to put D. putting on
答案：D.应改为 have. suggest， insist， order， demand， request， command， require等动词引导宾语从句时， 要用虚拟语气，谓语动词要should (可以省略)+原形动词。 (2002)
51. We strongly suggest that Smith is told about his physical condition as soon as possible.
答案：C， 改为be told， (2003/11)
42. The doctor advised her that she enough rest before going back to work.
A. to get B. get C. gets D. got (B， 0401)
四、在某些主语从句中的虚拟语气
⑴ It is …that引导的主语从句中，从句的谓语动词要用should+原形动词，should可以省略。suggest，propose， order， require， desire， ask
⑵ It is + 形容词+that引导的主语从句中，从句的谓语动词要用should+原形动词，should可以省略。important， necessary， vital， desirable， preferable， advisable， urgent， esseneial， requested，ordered
It is strange that he(should)go himself.真奇怪，他怎么自己独自去呢?
29、It‘s desired that she _____ to teach us at least twice a week. (C， 97年)
A. comes B. will come C. come D. may come
43 、It is desirable that he _____. (B， 2000)
A.gives up trying B.give up trying C.would give up trying D.is going to give up trying
45、It‘s urgent that a meeting _____ before the final decision is made. (C， 2003)
A. will be arranged B. must be arranged C. be arranged D. would be arranged
24. It‘s vital that enough money collected to get the project started.
A. is B. be C. must be D. can be (B， 0411)
五、在某些表语从句和同位语从句中的应用， 形式：should + 动词原形，should可省略。 表语前及同位语that前的名词：suggestion， proposal， motion， order， request，plan， idea， advice
My suggestion is that we (should) send a few people to help the other groups.
我的建议是我们派几个人去帮助其他小组。
47. Her suggestion that everybody _____ was not appreciated. (A，同位语从句，2001)
A. sing a song B. sang a song C. sung a song D. singing a song
48. The general's command was that the soldiers _________their fort and carry out more important tasks. (B，表语从句，2002)
A. would leave B. leave C. left D. have left
六、以as if，as though引导的方式状语从句中
⑴ 表示对现在的情况有所怀疑，动词用过去式
1、He talks as if he _____ everything in the world.
A. knows B. knew C. had known D. would have known
(答B.本句表示说话人对现在的情况有所怀疑，用过去时。)
2、You are talking as if you had seen them
你谈的那么起劲，好像你真的见过似的。(表示想象中的过去的动作)
⑵ 表示对过去的情况有所怀疑，动词用过去分词
七、用在由last， for fear that， in case(免得，以防万一)引导的目的状语从句，表示忧虑或担心。 形式：should + 动词原型， should不能省略
27. I wrote it down_________I should forget it. (2002)
A. in case B. in case of C. in order that D. for fear of
答：A.in case：(连词)。本句意思：我写了下来，免得忘了。又如：Keep the window closed in case it rains.把窗子关好，以防下雨。in case of (介词短语)：假使、如果发生。In case of fire， ring the alarm bell.如遇火警，即按铃。In order that (连词，引导目的状语从句)为了…In order that he should not be late ， his mother woke him at 6. 为了不使他迟到，母亲在6点种叫醒他。for fear of：(介词)生怕、以免。She left an hour early for fear of missing her train. 她提早一小时离开以免误了火车。
59. Written applications should be sent to us in case _____ some problems with the electric version. (C，2002)
A. there will be B. there is C. there be D. there was
八、would rather (that) + 动词过去时，表示没发生的动作
45、I‘d _____ you didn’t touch that， if you don‘t mind. (A，98)
A. rather B. better C. happier D. further
46、I am too busy these days. I would rather all of you ____ next month for a dinner.
A. come B. would come C. came D. have come (C，2002)
九、It is (high) time (that)…引导的定语从句中，动词用过去时， “(早就)该干…”未发生
43、It‘s high time we _____ something to stop traffic accident. (C， 96)
A. do B. will do C. did D. must do
2、Don‘t you think it is time you _____ smoking? (B，99)
A. give up B. gave up C. would give up D. should give up
43. Let‘s finish our homework in a few seconds， it’s time we . (A， 0411)
A. played football B. will play football C. play football D. are playing football