表虚拟的时间 if从句谓语形式 主句谓语形式
现在： did / were would (should, might, could)+do
过去： had done/ had been would (should/might/could)+have done(been)
将来： were to/ should+do would (should, might, could)+do
与现在事实相反：if i had enough money, i would buy a book.
与过去事实相反：if i had had enough money, i would have bought a book.
与将来事实相反：if i were to have enough money, i would buy a book. if i should have enough money, i would buy a book.
had i had enough money, i would have bought a book. were i to have enough money, i would buy a book.
should i have enough money, i would buy a book.
(对过去事实虚拟+对现在事实虚拟) if i had studied english at school, i could read the english novel now.
(对现在事实虚拟+对过去事实虚拟) if she were not so careless, she wouldn’t have made such a mistake.
what would i have done without you? but for their help, i would not have finished the task.
given more time, i would have been able to finish the test.
(1) ask, advise, beg, command, demand, decide, desire, insist, order, prefer, propose, require, recommend, request, suggest, urge等表示命令、要求、建议等含义的动词后的宾语从句中，谓语动词用(should)+动词原形,
eg. i suggest / suggested that we (should) go tomorrow.名词从句虚拟语气
(2) it is +(形容词/过去分词/特定名词)+that的从句中，形容词主要是表示令人吃惊的、重要的、必要的、关键的等词汇。形容词：astonishing, amazing, advisable, appropriate, crucial, desirable, essential, important, imperative, keen, necessary, natural, normal, odd, proper, preferable, strange, sorry, shocked, surprising, urgent, unusual, vital等。名词从句虚拟语气
(3) 过去分词：decided, desired, demanded, ordered, requested, recommended, suggested等;名词：advice, decision, desire, demand, suggestion, motion, pray, resolution, wish, preference, proposal, recommendation, requirement, idea, order等
wish… I wish I could quit you． 《断背山》if only… if only i were taller. (与现在事实相反)/
if only he had followed your advice! (与过去事实相反) /if only the rain would stop. (与将来事实相反)
it is (high/about) time… it is time you thought about your future.
would rather… i would rather you didn’t speak rudely to her. (与现在事实相反)
lest…, in case…, for fear that…（引导的是目的状语从句，但可归入第六点(名词从句虚拟)，这是因它们答案特征相同，即 (should)+动词原形。eg. he took his umbrella lest it should rain.
1. If I _________ the opportunity I would not have missed it. A) had given C) had been giving B) was given D) had been given
2. If we _______ yesterday, we _________ the work. A) weren't interrupted.., would finish B) didn't interrupt.., would have finished
C) hadn't been interrupted.., would have finished D) hadn't interrupted.., would have finished
3. Ask him to ring me up if you ____________ him. A) should see C) .saw B) would see D) will see
4. Your examination results were quite satisfactory, but ________ if you had spent less time in playing football?
A) wouldn't they have been better C) won't they be better B) wouldn't they be better D) won't they have been better
5. I didn't know this Picasso exhibit was closed, but I wouldn't have been able to come even if _________ about it.
A) I know C) I have been knowing B) I'd known D) I've known
6. If he ___________ hard in the past five years, things wouldn't be going so smoothly.
A) had not been working C) was not working B) has not been working D) were not working
7. "Do you think the thief entered through the garage door?" "No. If he had, I don't believe he __________ the living room window."
A) would have broken C) has broken B) had broken D) broke
8. I wish that you hadn't had such a bad headache because I'm sure that you ________ the concert.
A) will enjoy C) would enjoy B) will have enjoyed D) would have enjoyed
9. I'd rather you __________ anything about it for the time being. A) do B) didn't do C) don't do D) didn't
10. He doesn't dare to leave the house in case ___________.
A) he will recognize C) he is recognized B) he should be recognized D) he recognize
11. He is working hard for fear that he ___________ .
A) fell behind C) should fall behind B) may fall behind D) would fall behind
12. The driver looked over the engine carefully lest it _________ on the way.
A) breaks down C) would break down B) broke down D) should break down
13. It is highly desirable that a new chairman ___________ for the committee.
A) will be elected C) elect B) is elected D) be elected
14. It is requested that every student ___________ a plan for the next semester.
A) makes B) will make C) make D) would make
15. The librarian recommended that the professor __________ the newly published book.
A) borrow C) should have borrowed B) borrowed D) borrowing
16. If they _________ the contract ahead of time, they could not have missed the plan.
A) signed C) would have signed B) had signed D) should sign
17. I don't think it advisable that he _________ to the job since he has no experience.
A) be assqgned C) is assigned B) will be assigned D) has been assigned
18. What do you think of his proposal that we __________ put on a play at the English evening?
A) will B) should C) has D) have
19. He must have missed the train, otherwise he _________ then.
A) should arrive here C) would have arrived here B) has arrived here D) arrived here
20. But for friction, people _________ neither walk, nor even stand up.
A) can B) were able to C) will be able D) could
21. Mr. Johnson prefers that _________ with him personally.
A) she speaks C) she speak B) she will speak D) she would speak
22. You _________ yesterday, if you were really serious about the job.
A) ought to come C) ought to be coming B) ought to have come D) ought have come
23. The old worker urged that we __________ cheaper materials instead.
A) use B) used C) would use D) will use
24. Suppose/Supposing you _________ him now, what would you say to him?
A) meet B) met C) have met D) would meet
25. His father had hoped that he ________ into business.
A) would have gone C) can go B) will go D) would go
26. Helen doesn't know how much I spent in repairing the house; if she ever found out, I'm sure she __________ me.
A) would never forgive C) does never forgive B) never forgives D) will never forgive