学习啦【百科知识】 编辑：谢君 发布时间：2016-09-20
虚拟条件句从时间上又分为与现在事实相反，与过去事实相反，与将来事实可能相反三种情况。表示与现在事实相反的，if从句用过去式，主句用would (或could ,should ,might)加原形动词。与过去事实相反的，if从句用过去完成时，主句用would(或could ,should ,might)+have done结构。与将来事实可能相反的，if 从句用should (或were to )加动词原形，主句用would加动词原形。
1、If a better material _____, the strength of the part would have been increased.
A. had been used
B. had been using
C. being used
2、Had the weather been good, the children _____ out for a walk.
A. had gone
B. could have gone
C. would go
(答案：B。与过去的事实相反。当if从句中含有were, had, should这三个词时，if可以省略，主谓倒装。)
suggest (suggestion),propose(proposal),advise (advice)demand, insist, order, request, require, recommend, desire, ask, decide等。在这些从句中，谓语形式为should加动词原形，should可以省略。
例：The general’s command was that the soldiers _____ their fort and carry out more important task.
A. would leave
D. have left
三、在It is desired (或desirable), It is important等结构后面的主语从句中，动词用原形或should+原形动词。这些结构有：
“It is suggested”, “It is requested”,“It was ordered”, “It is necessary”, “It is essential”, “It is vital”, “It is urgent”,“ It is impossible”, “It is preferable”, “It is advisable”, “It was proposed”等。
例：It’s desired that she _____ to teach us at least twice a week.
B. will com
D. may come
四、would rather, as if/though 以及wish后边that从句中虚拟语气的运用。
1、I am too busy these days. I would rather all of you _____ next month for a dinner.
B. would come
D. have come
(答案：C。would rather 后面的从句中，动词用过去式。)
2、He talks as if he _____ everything in the world.
C. had known
D. would have know
3、You look as if you had seen a ghost.
(此句中as if 后边是说话人想象中的动作，所以用过去完成时。)
4、I wish I knew his address.
5、Peter wishes that he _____ law instead of literature when he was in college。
A. could study
C. had studied
D. would study
五、在It is (high) time后边的that从句中，动词用过去式，表示该做某事了。
例：Don’t you think it is time you _____ smoking?
A. give up
B. gave up
C. would give up
D. should give up
1. more careful, his bus would not have knocked into the tree.
A. If the driver were B. Had the driver been
C. Should the driver be D. If the driver would have been
2. the football competition, I would have gone to the concert yesterday.
A. In spite of B. But for C. Because of D. As for
3. Look at the terrible situation you are in! If only you my advice!
A. listen to B. would listen to C. had listened to D. have listened to
4. Had Henry received two more votes in the last election, he our monitor now.
A. must have been B. would have been C. were D. would be
5. If the athlete won today, he eight races in a game.
A. would have won B. won C. must have won D. did have won
6. It is time that our mayor measures to protect the poor in the street.
A. takes B. took C. has taken D. taking
7. If I had read the report, I _______ you all about it now.
A. would tell B. will tell C. have told D. would have told
8. — It’s a pity you didn’t won the competition.
— I had had more practice.
A. If only B. As if C. If not D. As with
Key: 1-5 BBCDA