1. 虚拟语气用在 suggest, demand, insist, ask, move, advise. desire, order, propose, require, recommend, request, maintain, vote 等表示建议，命令，请求的动词后的宾语从句中，从句的谓语用 should + 原形动词，但美国英语中常要省去 should 。例如：
- I suggest we start at once.
- They propose that you (should) read the rules carefully.
- The commander ordered that the soldier fire at the enemy.
- He insisted that he go there on foot.
- I move that the meeting be adjourned. 我提议休会。 move:(在会议上)提议，动议
Example:
He insisted that we all ______ in his office at one o'clock.
a. be b. to be c. would be d. shall be
He asked that it ______ done right away.
a. is b. be c. shall be d. must be
He recommended that John ______ with him.
a. must go b. went c. will go d. go
2. 虚拟语气用在 It is + 形容词（或过去分词）+ that... .的主语从句中，表示要求，建议，提议，命令，请求等，英国英语中从句的谓语用“should +原形动词（或完成式）构成”，而美国英语中则要求用原形动词。该句型中常用的形容词或过去分词有：advisable, desirable, essential, important, better, keen, natural, necessary, probable, possible, strange, vital, desired, demanded, requested, suggested, recommended, required 等。例如：
- It is necessary that the machine (should) be oiled once a week.
- It is important that everyone (should) obey the law.
- It is suggested that you take a walk after supper.
Example:
It is necessary that he ______ in time to attend the meeting.
a. come b. came c. would come d. need come
It was proposed that the matter ______ discussed at the next meeting.
a. would be c. will be c. was d. be
It is strange that she ______ in the last examination.
a. should have failed b. have failed c. would fail d. failed
3.虚拟语气用在与表示建议，要求，提议，命令，请求等意思有关的同位语从句和表语从句中，英国英语中要求从句谓语用“ should + 原形动词”，而美国英语中则要求用原形动词， 但在 as if, as though引导的表语从句中，从句中谓语用动词过去式或过去完成式，表示对现在或过去的虚拟。例如：
- He complied with the requirement that the experiment (should) be done tomorrow.
他同意明天再做实验的要求。虚拟语气用在其它名词性从句中 - He looks as if he were tired.
他面带倦容。 - We agree to the suggestion that they (should) work on night shifts in turn.
我们同意轮流值夜班的建议。 - His order is that you (should) send the materials to the work site at once.
他的命令是你们要把材料立即送到工地。
Example:
Your advice that she ______ till next week is reasonable.
a. will wait b. is going to wait c. waits d. wait
Jane appears as though she ______ the secret.
a. knows b. has known c. had known d. knew
He looked as if he______ ill for a long time.
a. was b. were c. has been d. had been
4.虚拟语气用在 It is (high, about) time (that) 句型中，定语从句中谓语用动词过去式，意指将来。例如：
- It is time (that) we went home.
- It is high time we had the meeting.
- It is time you left.
- It is time that I was off.
注：如果主语是单数第一，三人称，动词 be常用 was 。
Example:
We've been sitting here doing nothing about it for days. It's time we ______ the problem.
a. shook hands with b. got to brass tacks with
c. got to grips with d. reached the bottom of
词组 get (or come) to grips with 为“开始努力对付”。
It is high time we _______ off.
a. are b. were c. be d. will be
It is ______ we did something about redecorating the sitting room.
a. high time b. long time
c. good time d. full-time
练习题：
1. The doctor suggested that he ______ a short leave of absence.
a. will take b. would take c. take d. took
2. We demand that atomic weapons ____ .
a. be prohibited b. will be prohibited
c. are prohibited d. ought to be prohibited
3. It was suggested that transistors _____ in such devices.
a. should be used b. should use
c. can be used d. were using
4. The tutor recommended that she _______ this book.
a. must buy b. buy
c. should have bought d. buys
5. The housemaster was strict. He requested that we ______ television on week nights.
a. not watch b. must not to watch
c. not be watching d. have not watched
6. My father did not go to New York, the doctor suggested that he ______ there.
a. not to go b. won't be
c. not go d. not go to
7.I demanded that the students each ______ a plan for the summer vacation.
a. would make b. will make c. make d. made
8. It is surprising enough that such a horrible thing ____ there.
a. happened b. will happen
c. should happen d. has happened
9. It was urgent that she ______ the master immediately.
a. call b. calls c. called d. would call
10. He looks as if he _____ nothing about it before.
a. knows b. had known
c. has known d. wouldn't know
11.My idea is that we ______ the challenge.
a. ought accept b. will accept
c. accept d. are accepted
12. The sun rises in the east and sets in the west, so it seems as if the sun ______ round the earth.
a. is circling b. has circled
c. should circle d. were circling
13. It was suggested at the meeting that effective measures _______ to solve the problem.
a. be taken b. must be taken
c. were taken d. take
14. It's advisable that he ______ with a clearly defined goal in mind.
a. must go b. go c. will go d. goes
15.It seemed as if all of sudden the animal _____ danger in the air.
a. has smelt b. had smelt
c. smelt d. would smell
16.It is better that the book ______ on the low stool.
a. put b. puts
c. should be put d. be put
17.He moved that the report ______.
a. should accept b. should be accepted
c. be accept d. would be accepted
18.The professor gave orders that the test ______ before 5:30.
a. be finished b. will be finished
c. will finish d. shall finish
19.It's time he ______ something for his coming examination.
a. do b. does c. will do d. did
20.It was essential that all the necessary documents ______ to the dean's office before Friday.
a. be handed in b. must be handed in
c. had been handed in d. should hand in
21.It is highly desirable that a new president _____ for our institute.
a. appointed b. be appointed
c. has been appointed d. is appointed
22. The government ordered that the pollution problem of this city ______ within six months.
a. would solve b. would be solved
c. should be solved d. must solve
23. It is natural that much research ______ to overcome corrosion.
a. should make b. will make
c. is made d. should have been made
24. It is important that a consultant engineer ______ familiar with modern developments.
a. is b. being c. be d. has been
25. Since her blood pressure is much higher than it should be, her doctor insists that she _____.
a. will not smoke b. is not smoking
c. didn't smoke d. not smoke
