1. If the earth suddenly _______ spinning, we would all fly off it.A. had stoppedB. stoppedC. has stoppedD. would stop2. It is highly desirable that a new president _______ for this college.A. appointedB. be appointedC. is appointedD. has been appointed3. It was proposed that the matter _______ discussed at the next meeting.A. will beB. wasC. isD. be4. He didn’t go to the party, but he does wish he _______ there.A. had beenB. has beenC. would have beenD. would be5. It was essential that the application forms _______ back before the deadline.A. must be sentB. would be sentC. be sentD. were sent6. My cat would not have bitten the toy fish _______ it was made of rubber.A. if she has knownB. if she knewC. she should have knownD. had she known7. That tree looked as if it _______ for a long time.A. hasn’t wateredB. didn’t waterC. hadn’t been wateredD. wasn’t watered8. It is necessary _______ the dictionary immediately.A. that he will returnB. that he returnedC. that he returnD. that he has to return9. You’re talking to me as if I _______ an expert.A. amB. wasC. have beenD. were10. “Mary wants to see you today.”“I would rather she _______ tomorrow than today.”A. comesB. cameC. should comeD. will come11. I t’s getting rather late. It’s time we _______.A. are goingB. wentC. goD. must go12. It was unkind of you to say that ；you really _______ done so.A. should notB. should not haveC. need notD. must not13. This experiment _______ last week.A. should be doneB. should have been doneC. should have doneD. should do14. If it had rained last night, the roads _______ wet now.A. would have beenB. wereC. must beD. would be15. _______ you were coming today, I’d have met you at the airport.A. Have I knownB. I have knownC. Had I knownD. I had known16. If the sun _______ tomorrow, what would we do?A. would not riseB. should not riseC. had not riseD. does not rise17. Without your help, we _______ so much.A. wouldn’t have achievedB. will not achieveC. didn’t achieveD. don t achieve18. Care must be taken in using this method lest overflow _______.A. should occurB. occursC. occurredD. will occur答案与解析1. B如果地球突然停止转动，我们都将飞离出去。
虚拟语气。
if 引导的假设性条件状语从句，表达与现在事实相反的假设情况时，从句动词结构使用过去式，主句动词使用would + V原形。
2. B一位新校长被任命来这所大学，这是最好不过的了。
虚拟语气。
It is + adj . + that...主语从句中，动词使用should + V原形，should 可以省略。
常用形容词有essential, necessary, desirable, incredible, important, imperative等。
3.D有人提议这个问题下次会议再讨论。
虚拟语气。
It is + V过去分词+ that...从句中，动词使用should + V原形，should 可以省略。
动词一般含有“建议、决定、要求、命令”之意。
4.A他没有去参加宴会，但是他着实希望他（那时）在那儿。
虚拟语气。
wish后的宾语从句中，表达与过去事实相反的愿望，谓语动词使用过去完成时。
5.C申请表在截止日期前送回去，这是非常必要的。
虚拟语气。
解析同2 。
6.D如果我的猫知道玩具鱼是由橡胶做成的话，她就不会抓咬它了。
虚拟语气。
if 引导的非真实性条件状语从句，表达与过去事实相反的假设情况时，从句动词结构使用过去完成时，主句动词使用would + have done。
7.C那棵树看上去好像已经很长时间没有浇水了。
虚拟语气。
as if在引导的方式状语从句中表示“仿佛，好像” ，如果表示与过去事实相反，对过去情况的推测，谓语动词则使用过去完成时。
8.C他要立即归还字典，这是极为必要的。
虚拟语气。
解析同2 。
9.D你（现在）同我说话（的样子）仿佛我是个专家。
虚拟语气。
as if在引导的方式状语从句中，表示“仿佛，好像”，如果表示与现在事实不符，对现在情况的推测，谓语动词则使用过去式，如果是be动词，则使用were。
10. B“玛丽今天想见你。
”“与其今天来，我宁愿她明天来。
”虚拟语气。
would rather后的从句中，如果表示与现在或将来事实不符的情况，谓语动词使用一般过去时。
11.B天色很晚了，我们该走了。
虚拟语气。
It is (about / high) time (that)后的从句中，表示早该做而未做的事，含“建议”的意味，谓语动词使用一般过去时。
12.B你说那些话太不友善了，你本不该那么做。
虚拟语气。
情态动词should not + have done结构表示“本不该……”。
13.B这项实验本该上周做的。
虚拟语气。
解析同12 。
情态动词should + have done结构表示“本该……”。
14.D如果昨晚下了雨，现在路上就会湿。
虚拟语气。
if 引导的错综时间的非真实性条件句，如果从句表示与过去事实相反的情况，主句表示与现在事实相反的情况，则从句动词使用过去完成时，主句动词使用would + V原形。
15.C如果我早知道你今天来，我就会去机场接你。
虚拟语气。
if 引导的非真实性条件状语从句，表达与过去事实相反的假设情况时，从句动词结构使用过去完成时，主句动词使用would + have done。
如果从句连词if省略，则呈倒装语序。
16.B万一明天太阳不升起，我们该怎么办？虚拟语气。
if 引导的非真实性条件状语从句，表达与将来事实相反的假设情况时，从句动词结构使用should +V原形或were to do ，主句动词使用would +V 原形。
17.A没有你的帮助，我们就不会取得如此多的成就。
虚拟语气。
有时假设的情况并不以条件从句的形式表现，而是通过一个介词短语、上下文或其他方式表现，此为含蓄条件句。
与过去情况不符，动词使用would+ have done。
18. A必须小心使用这种方法，以防溢流发生。
虚拟语气。
以lest ，for fear that和in case引导的状语从句中，谓语多使用should + V原形。