⾼中英语语法讲解--虚拟语⽓
1. 语⽓的定义和种类
（1）语⽓的定义
语⽓是动词的⼀种形式，它表⽰说话⼈对某⼀⾏为或事情的看法和态度。
（2）语⽓的种类
A. 陈述语⽓
表⽰动作或状态是现实的、确定的或符合事实的，⽤于陈述句、疑问句和某些感叹句。
We are not ready.
Did it rain all day yesterday?
What a fine day today！
B. 祈使语⽓
表使说话⼈的建议、请求、邀请、命令等。
Be careful.
Don’t forget to close the window.
Open the door, please.
C. 虚拟语⽓
表使动作或状态不是客观存在的事实，⽽是说话⼈的主观愿望、假设或推测等。
2. 虚拟语⽓
⼀. 虚拟语⽓在条件句中的应⽤
学习虚拟语⽓在条件句中的⽤法之前我们必须清楚条件句的种类：条件句有真实条件
句与⾮真实条件句(或称虚拟条件句)两种。真实条件句所表的假设是可能发⽣或实现的，
句中的条件从句与结果主句都⽤陈述语⽓。如：
If it doesn’t rain tomorrow, I will go for a picnic. 假若明天不下⾬，我就去野餐。
Oil floats if you pour it on water. 你如把油倒在⽔⾥，油就浮起来。
虚拟条件句所表的假设则是不可能或不⼤可能发⽣或实现的，句中的条件从句与结果
主句皆须⽤虚拟语⽓。
条件从句
主句
与现在事实相违
背
过去式（动词是be⽤were）
should / would/could/might + 动词
原形
与过去事实相违
背
had + 过去分词
should / would/could/might + have
+过去分词
与未来事实相违
背
1) should + 动词原形
2) were + 动词不定式
3) 过去式（动词是Be也可以⽤
were）
should / would/could/might + 动词
原形
1. 与现在事实相反的虚拟条件句，条件从句的谓语⽤动词的过去式 (be的过去式⽤
were), 主句的谓语⽤should （would, might， could）+动词原形。
如：
If it were not raining, we should go for a picnic.如果现在不下⾬的话，我们就出去野餐
了。
（事实是：天在下⾬，我们不能出去野餐。表⽰愿望。）
If he came here, he might be able to help you. 如果他来这，他就能够帮助你了。
（事实是：他没来这，他不可能帮助你。表⽰对他的良好印象。）
2. 与过去事实相反的虚拟条件句，条件从句的谓语⽤had+过去分词，主句的谓语⽤
should （ would, might， could）+ have ＋过去分词。
如：　She would have gone to the party if she had been invited.　要是当初她被邀请的话，她就会去参加这次聚会了。
（事实是：当时没有⼈邀请她，因此，她没有来参加聚会。表⽰后悔。）
If she hadn't called me, I would have overslept this morning.
今天早上，她要是不叫我的话，我就会睡过头了。
（事实是：她今天早上叫我了，我没有睡过头。表⽰感激。）
3. 与将来事实可能相反的虚拟条件句，条件从句的谓语⽤动词的过去式(be的过去式⽤
were)； should＋动词原形；were to＋动词原形，主句⽤should （would, might， could）+动
词原形。
如：　If I were to be twenty years old next year, I would take the course of French.
明年我要是⼆⼗岁，我就会学法语。
（事实是：我现在已经⽼了，明年我学不了法语了。）
If it should fail, I would try again.要是失败了，我会再试⼀次。
（事实是：有可能失败，可我会再试。表⽰未知。）
虚拟过去式有时并不表⽰“不⼤可能实现的假设”，⽽是表⽰⼀种希望或不希望发⽣的动
作。
如：　If we caught the early train, we’d get there by lunch time.
假如我们赶上早班⽕车，到午饭时间我们就会到达那⾥了。(表希望)
If we missed the train, we should have to wait an hour at the station.
假如我们赶不上这班⽕车，我们就得在车站等⼀⼩时。（表不希望）
4. 混合型的条件句
当条件从句与主句所表的时间不⼀致时，虚拟语⽓的形式应作相应的调整。主句和从
句的谓语动词并不相互呼应，这种条件句叫混合条件句。较多见的混合型条件句是从句⽤
过去完成时（指过去⾏为），⽽主句⽤⼀般时（指⽬前状态）。
He would pass the test if he had taken my advice．如果他听了我的劝告，他现在会通过考
试。
If I had spoken to him yesterday, I should know what to do now.
假如昨天我对他说了，现在我就知道该怎么办了。
You would be much better now if you had taken my advice.
假如你接受了我的意见，你现在就会好得多。
如条件从句⽤if I were...，主句则可⽤表任何时间的虚拟形式。
如：　If I were not busy, I would have come.
假如我不忙，我就会去了。(were表过去)
If I were you, I would go.
假如我是你，我会去的。(were表现在)
⼆. 连词if的省略（倒装）
如果虚拟条件句的谓语部分有were，had和should时，可省略if，把were，had和should
放到从句主语前⾯去，多见于书⾯语。
Had you not helped me， I should have failed.要是没有你的帮助，我就失败了。
Were you in my position, you would do the same. 假如你处在我的地位，你也会这样⼲
的。
Should they attack us, we’ll wipe them out completely.
假如他们进攻我们，我们就把他们彻底消灭⼲净。
例：1. _________ he would have succeeded in the examination.
A. Had he worked hard
B. If he worked hard
C. If he works hard
D. If he has worked hard
2. _______ it rain tomorrow, we would stay at home.
A. Should
B. Be
C. Were
D. Will
3. _______, he would teach us how to solve the problem.
A. Were he here
B. Was he here
C. If he is
D. Is he here
4. _________, we should be glad.
A. Were they to arrive tomorrow
B. They were to arrive tomorrow
C. They would arrive tomorrow
D. They arrive tomorrow
5. _______ the clouds, you would find the airplane in the sky easily.
A .Were it not for
B. If it had not been for
C. If it were not
D. Had it not been for
答案：1—5 AAAAA
三. 含蓄条件句
虚拟条件句中的条件从句有时不表出来，只暗含在上下⽂中，这种句⼦叫做含蓄条件
句。含蓄条件句⼤体有三种情况。
1) 条件暗含在短语中。
如：　But for your help we couldn’t have succeeded in the experiment.
如果没有你的帮助，我们的实验是不会成功的。(暗含在分词短词but for your help)
What would I have done without you? 如没有你，我会怎么办呢？(条件暗含在介词短语
without you 中)
It would be easier to do it this way. 这样做会⽐较容易。
(条件暗含在不定式短语 to do it this way中)
This same thing, happening in wartime, amount to disaster.
同样的事，如发⽣在战时，就会酿成⼤祸。(条件暗含在分词短语happening in wartime
中)
He must have the strength of a hippopotamus, or he never could have vanquished that great
beast. 他⼀定是⼒⼤如河马，否则他绝不会击败那只庞⼤的野兽。(暗含条件是连词or)
Alone, he would have been terrified. 如是单独⼀⼈，他是会感到害怕的。(暗含条件是alone)
2) 条件暗含在上下⽂中。
如：　You might stay here forever. 你可以永远待在这⼉。(可能暗含if you wanted to)
We would have succeeded. 我们本来是会成功的。(可能暗含if we had kept trying)
Your reputation would be ruined. 你的名誉会败坏的。(可能暗含 if you should accept it)
3) 在不少情况下，虚拟式已变成习惯说法，很难找出其暗含的条件。
如：　You wouldn’t know. 你不会知道。
I would like to come. 我愿意来。
四. 不⽤if引导的条件从句
虚拟条件句中的条件从句除⽤if引外，还可⽤when, unless, lest, suppose, as if, for fear, in
case, on condition 等词语来引导。
如：　The peasants prepared to feed the city when it should be freed.
农民已准备在这座城市解放后供给粮⾷。
Lest you should not have heard all, I shall begin at the beginning.
我怕你没有听全，所以我再从头开始讲⼀遍。
Unless I were well, I wouldn’t be at school. 除⾮我好了，否则我不会上学。
Suppose you were given a chance to study in America , would you accept?
假如给你⼀个到美国学习的机会，你会接受吗？（suppose 或 supposing =what if）
Supposing it were so？（=Supposing it were so，what would happen？）
要是这样的话，会怎么样呢？
He can use the bicycle on condition that he should return it tomorrow.
如果明天能还回来，他就可以借⽤这辆⾃⾏车。
In case I forget , please remind me of my promise 如果我忘了，请提醒我的诺⾔。
Susan is walking slowly ,as if she were tired. 苏珊⾛得很慢，就像是累了似的。
与if⼀样，上述词语所引导的条件从句亦可⽤直陈语⽓，表可能实现或发⽣的事。
虚拟语⽓补充讲解（第⼆课时）
虚拟语⽓除主要⽤于条件句（也就是状语从句）外，还可⽤于主语从句、宾语从句、
表语从句、定语从句等。
1. 虚拟语⽓在主语从句中的应⽤
“常⽤在It is (was)+形容词 / 过去分词+that引导的主语从句”的句型中的主语从句要⽤虚
拟语⽓。主语从句的谓语⽤should+动词原形(或should+have+过去分词)或只⽤动词原形(尤
其是美国英语)。should在此是助动词，本⾝并⽆实义，这种主语从句中的should有时有感
情⾊彩。
It's important that we（should）work out a plan. （带有“要求”的含义）
It's better that he go at once. （带有“建议”的意思）
☆ ⽤于本句型的形容词并不多，常见形容词有：necessary，important，best, right,
impossible，preferable，desirable, imperative, advisable，essential，reserved，urgent， 等。
It is necessary that he（should）be sent there at once．　It's strange that he should say so.　I was glad that he should go.
It is important that we should speak politely.
It is a pity that she should fare so badly.
It's right that you should think that way.
☆⽤于本句型中的过去分词就是表⽰提议要求、命令等动词的过去分词，如suggested，
settled, required，requested，demanded，urged，decided, proposed，ordered，desired，
advised等。
It is requested that Professor Liu（should）give us a lecture．　It is desired that we（should）get everything ready by tonight．
I’m ashamed you should have done such a thing.
It has been suggested that the meeting（should）be put off．有⼈建议推迟会议。
It is settled that you leave us, then?
注意：这种句型中的主语从句也可⽤陈述语⽓，如：It was important that he made an explicit
statement on this score last week. 他上个星期对于这⼀⽅⾯做了明确的说明，这是很重要的。
句型总结：
It is necessary that…
It is important that…
It is natural that…
It is strange that…
It is surprising that…
It is impossible that…
It is great pity that…
It will be better that…
It is suggested that…
It is ordered that….
It is demanded that…
2. 虚拟语⽓在宾语从句中的应⽤
1). 宾语从句在表⽰提议、要求、命令、意志等动词后，其谓语⽤should+动词原形或
只⽤动词原形的虚拟语⽓，作为suggest，request，demand，urge，propose，prefer，
advise，insist，require，order，command，maintain，ask，object, arrange, desire等动词的宾
语。
如：
The doctor suggested that he not go there．医⽣建议他不要去那⾥。
He suggested that we should leave early. 他建议我们早点动⾝。
The judge ordered that the prisoner should be remanded. 法官命令被告还押。
例：1. The teacher insisted that every student _______ every other line.
A. writes
B. write
C. would write
D. wrote
2. Jack’s father insists ______ in this hotel.
A. not staying
B not to stay
C. that he not stay
D. staying not
3. They insisted that you _______ them a quick answer.
A. should give
B. gave
C. must give
D. would give
4. The guard at the gate insisted that everybody _______ the rules.
A. obeys
B. obey
C. will obey
D. would obey
答案：1—4 BCAB
注：1）、suggest 为“建议去做…; 命令…”从句⽤should + do
为“ 说明； 暗⽰”, 从句⽤过去时或过去完成时。
1. The doctor suggested that I should take the medicine three times a day.
2. The doctor suggested that my grandmother had caught a bad cold.
3. The expression on her face suggests that she knew the secret.
4. They suggested that these books ______ at once.
A. should take away
B. would be taken away
C. be taken away
D. take away
5. I suggested a meeting _______ to discuss the matter.
A. will be held
B. would be held
C. should hold
D. be held
6. His silence at the meeting suggested ________ to your plan.
A. didn’t agree
B. hadn’t agreed
C. wouldn’t agree
D. shouldn’t agree
答案：4—6 CDA
2）、insist “坚持要去做…，坚持应该去做”，从句⽤should + do
为“坚持表明，坚持说/解释”， 从句⽤过去时或过去完成时。
1. She insisted that she ______ ill of him behind him, but he didn’t believe.
A. hadn’t spoken
B. shouldn’t speak
C. wouldn’t speak
D. not speak
2. He insisted that we ______ the boy to hospital.
A. take
B. took
C. would take
D. will take
3. He insisted that he _______ our car.
A. should steal
B. would steal
C. hadn’t stolen
D. steal
4. The teacher commanded that all his students ______ their homework after class.
A. would hand in
B. should hand in
C. handed in
D. might hand in
5. The workers requested that their working conditions ______.
A. must be improved
B. be improved
C. would be improved
D. were improved
6. They required that the crops _______ harvested at once.
A. should be
B. be
C. are
D. must be
答案：1—6 BACBBA
2). wish的宾语的从句，表⽰愿望，常省去连词that。
☆ 从句的谓语动词可⽤过去式，表⽰现在的愿望（与现在事实相反），虽实现的可能
性不⼤，但仍有实现的可能。
I wish it were true．我但愿这是真的。
☆ 从句的谓语动词还可⽤“could（would，might）+动词原形”⽤来表⽰将来的愿望
I wish you would stay a little longer.我希望你再待⼀会⼉。
☆ 表⽰⽆能为⼒的过去愿望（与过去事实相反），可⽤“had +过去分词”或“could
（would，might）+have+过去分词”
I wish you had called yesterday．我希望你昨天来过电话。
We wish you had come to our New Year’s party.我们真希望你来参加了我们的新年联欢会。
例：7. I wish I _______ you yesterday.
A. saw
B. did see
C. had seen
D. were to see
8. —Have you visited the Science Museum?
—No, but I really wish I _______.
A. will
B. have
C. did
D. had
9. I wish that the rain ______ stop.
A. will
B. would
C may
D. can
答案：7—9 CDB
3). would rather, would sooner等表⽰愿望，其宾语从句常⽤虚拟过去式。
☆ 表⽰与现在和将来含义事实相反的虚拟语⽓要⽤动词的过去式
☆ ⽤过去完成式(had + 过去分词)表⽰过去事实相反的含义
I would rather you came tomorrow.我宁愿你明天来。
I’d sooner she left the heavy end of the work to some one else.我宁愿她把重活留给别⼈。
4). 有些动词，如think, expect, believe,其否定式的宾语从句亦可⽤should+动词原形。
如：
I never thought he should refuse.我万没有想到他会拒绝。
She did not expect that you should come.她没有预料你会来。
3. 虚拟语⽓在表语从句中的应⽤
名词suggestion，proposal，order，advice，demand等作主语，其后的表语从句中的谓
语动词⼀般使⽤虚拟语⽓，⽤should +动词原形或省略should。
My suggestion is that we (should) send a few soldiers to help them.　我的建议是我们应派⼏个战⼠去增援他们。
My advice is that you (should) treat her well.　我的忠告是你应该善待她。
He makes the demand that she (should) leave the place at once.　他提出⼀个要求，要求她⽴刻离开这个地⽅。
My suggestion is that we should tell him.我的建议是我们应该告诉他。
Our only request is that this should be settled as soon as possible.
我们唯⼀的请求就是尽快解决这个问题。
注意：虚拟语⽓也可以⽤于同位语从句。
如：There was a suggestion that Brown should be dropped from the team.有⼀项建议是布朗应
该离队。
4. 虚拟语⽓在定语从句中的应⽤
常⽤在It is time (that)…句型中，定语从句常⽤虚拟过去式
It is time the children went to bed.　孩⼦们早该上床睡觉了。（表⽰催促）
It's high time that he began to think how to deal with money.　他早该开始考虑如何与钱打交道。
It is time we left.我们该⾛了。
It is time we went to bed.我们该去睡觉了。
5. 虚拟式动词原形亦常⽤在独⽴句中，表愿望
Long live the Communist Party of China！中国共产党万岁！
God bless you! 上帝保佑你。
God damn it! 该死的！
The devil take you! ⻅见⻤鬼去吧！
So be it then. 就那样吧。
6. 虚拟时态与谓语动词时态的关系：从句句中的虚拟时态往往不不受全句句谓语时态的影
响。
1) ⽤用于主语从句句。试⽐比较：
It is important that he should know about this.他必须知道此事。
It was important that he should know about this.他必须知道此事。
2) ⽤用于宾语从句句。试⽐比较：
I suggest that we should go tomorrow.我建议我们明天⾛走。
I suggested that we should go the next day.我建议我们第⼆二天⾛走。
She said, “If I were a boy I would join the army.”她说，“我如是男孩，就参军。”
She said that if she were a boy, she would join the army.她说她如是男孩就参军。
但强调现在时刻的虚拟式在间接引语中需要遵守时态⼀一致的原则。试⽐比较：
“If I knew how it worked, I could tell you what to do,” he said.
“假如我知道它是如何运⾏行行的话，我就会告诉你该怎么办，”他说道。
He said that if he had known how it worked he could have told me what to do.
他说假如他知道它是如何运⾏行行的话，他就会告诉我该怎么办。
“If I knew the answer to all your questions I'd be a genius,” he said.
“我如知道你所有问题的答案，我就是天才了了。”他说道。
He said that if he knew the answer to all my questions, he’d be a genius.
他说他如知道我所有问题的答案，他就是天才了了。
但如果全句句谓语是虚拟语⽓气，其后从句句的时态则多受其影响，现在时态应随之⽽而变为
过去时态。
如：I would think he was wrong.我看他是错了了。(须⽤用was,试⽐比较：I think he is wrong)
It would seem that she was right. 她似乎是对的。(须⽤用was,试⽐比较：It seems that she is right)
专项训练：
1.I enjoyed the movie very much. I wish I _____ the book from which it was made.
A. have read　B. had read
C. should have read　D. are reading
2.You are late. If you _____ a few minutes earlier, you _____ him.
A. come; would meet　B. had come; would have met
C. come; will meet D. had come; would meet
3.The two students talked as if they _____ friends for years.
A. should be　B. would be
C. have been　D. had been
4.It is important that I _____ with Mr. Williams immediately.
A. speak　B. spoke
C. will speak　D. to speak
5.He looked as if he _____ ill for a long time.
A. was　B. Were C. has been　D. had been
6.If the doctor had come earlier, the poor child would not _____.
A. have laid there for two hours B. have been lied there for two hours
C. have lied there for two hours　D. have lain there for two hours
7.I wish that I _____ with you last night.
A. went　B. could go
C. have gone　D. could have gone
8.Let’s say you could go there again, how _____ feel?
A. will you　B. should you
C. would you　D. do you
9.I can’t stand him. He always talks as though he _____ everything.
how.
A. knew B. knows
C. has known　D. had known
10._____ the fog, we should have reached our school.
A. Because of　B. In spite of
C. In case of　D. But for
11.If you had told me in advance, I _____ him at the airport.
A. would meet　B. would had met
C. would have met　D. would have meet
12.Mike can take his car apart and put it back together again. I certainly wish he_____ me
A. teaches B. will teach
C. has taught　D. would teach
13.I would have told him the answer, had it been possible, but I _____ so busy then.
A. had been　B. were
C. was　D. would be
14.He’s working hard for fear that he _____.
A. should fall behind　B. fell behind
C. may fall behind　D. would fallen behind
15.If it _____ another ten minutes, the game would have been called off.
A. had rained　B. would have rained
C. have seen　D. rained
16.He suggested that they _____ use a trick instead of fighting.
A. should　B. would
C. do　D. had
17.My father did not go to New York; the doctor suggested that he _____ there.
A. not went　B. won’t go
C. not go　D. not to go
18.I would have gone to the meeting if I _____ time.
A. had had　B. have had
C. had　D. would have had
19.Would you rather I _____ buying a new bike?
A. decided against　B. will decide against
C. have decided　D. shall decide against
20.You look so tired tonight. It is time you _____.
A. go to sleep　B. went to sleep
C. go to bed　D. went to bed
21.—Why didn’t you buy a new car?
—I would have bought one if I _____ enough money.
A. had　B. have had
C. would have　D. had had
22.If she could sew, _____.
A. she make a dress B. she would have made a shirt
C. she will make a shirt　D. she would had made a coat
23._____ today, he would get there by Friday.
A. Would he leave　B. Was he leaving
C. Were he to leave　D. If he leaves
24.His doctor suggested that he _____ a short trip abroad.
A. will take　B. would take
C. take　D. took
25.The Bakers arrived last night. If they’d only let us know earlier,_____ at the station.
A. we’d meet them　B. we’ll meet them
C. we’d have met them　D. we’ve met them
26.If I _____ you, I _____ more attention to English idioms and phrases.
A. was; shall pay　B. am; will pay
C. would be; would pay　D. were; would pay
27.We might have failed if you _____ us a helping hand.
A. have not given　B. would not give
C. had not given　D. did not give
28.The law requires that everyone _____ his car checked at least once a year.
A. has　B. had
C. have　D. will have
29.It is strange that he _____ so.
A. would say　B. would speak
C. should say　D. will speak
30.Had I known her name, _____
A. or does she know mine?　B. and where does she live?
C. she would be beautiful.　D. I would have invited her to lunch.
31.He has just arrived, but he talks as if he _____ all about that.
A. know B. knows
C. known　D. knew
32.If I _____ the money, I would have bought a much bigger car.
A. possessed　B. owned
C. had　D. had had
33.He was very busy yesterday; otherwise, he _____ to the meeting.
A. would come　B. came
C. would have come　D. will come
34.The librarian insists that John _____ no more books from the library before he
returns all the books he has borrowed.
A. will take　B. took
C. take　D. takes
35.I left very early last night, but I wish I _____ so early.
A. didn’t leave　B. hadn’t left
C. haven’t left　D. couldn’t leave
36.I do not have a job. I would find one but I _____ no time.
A. had　B. didn’t have
C. had had　D. have
37.I wish that you _____ such a bad headache because I’m sure that you would have
enjoyed the concert.
A. hadn’t　B. didn’t have had
C. hadn’t had　D. hadn’t have
38.He insisted that we all _____ in his office at one o’clock.
A. be　B. to be
C. would be　D. shall be
39.Helen couldn’t go to France after all. That’s too bad. I’m sure she would have
enjoyed it if _____.
A. she’s gone　B. she’ll go
C. she’d gone　D. she’d go
答案：
1—5 BBDAD 6—10 DDCAD　11—15 CDCAA　6—20 ACAAD
21—25 DBCCC 26—30 DCCCD　31—35 DDCCB 36—39 DCAC
解析：
1.wish后⾯⽤虚拟语⽓，表⽰与过去事实相反⽤过去完成时。
2.条件句表⽰与过去事实相反，主句⽤过去将来完成时，从句⽤过去完成时。
3.as if后⾯如果表⽰真实情况就不⽤虚拟。
4.It is important that是主语从句的虚拟语⽓，从句⽤sb. should do的形式。
5.as if后⾯是真实情况，不虚拟。
6.lain是lie的过去分词，表⽰“躺”。
7.could have done表⽰“本来可以”。
8.与将来相反的虚拟语⽓，主句⽤过去将来时。
9.as if表⽰不可能发⽣的事情时⽤虚拟语⽓。
10.but for表⽰“要不是……的话”，通常与虚拟语⽓搭配使⽤。
11.in advance表⽰“事先”，表⽰与过去事实相反的虚拟语⽓。
12.wish的宾语从句表⽰发⽣在将来的愿望⽤过去将来时。
13.but的并列句表⽰真实情况，不⽤虚拟语⽓。
14.for fear that后⾯的状语从句⽤sb. should do的形式。
15.表⽰与过去事实相反，主句⽤过去将来完成时，从句⽤过去完成时。
16.suggest后⾯的宾语从句⽤sb. should do的形式。
17.suggest后⾯的从句⽤sb. should do的形式，should可以省略。
18.表⽰与过去事实相反，从句⽤过去完成时。
19.would rather的宾语从句⽤sb. did的形式。
20.It is time后⾯的定语从句⽤sb. did的形式。
21.第⼀个had是过去完成时，第⼆个had表⽰“有”。
22.would have done是过去将来完成时，表⽰与过去相反的虚拟语⽓。
23.这是虚拟语⽓的倒装形式，把if去掉，助动词提前。
24.suggest后⾯的从句⽤sb. should do的形式，should可以省略。
25.表⽰与过去事实相反，主句⽤过去将来完成时。
26.在虚拟语⽓中，不管什么⼈称，be动词都要⽤were的形式。
27.表⽰与过去事实相反，从句⽤过去完成时。
28.require后⾯的从句⽤sb. should do的形式，should可以省略。
29.It is strange that是主语从句的虚拟语⽓，从句⽤sb. should do的形式。
30.had I known是与过去相反的虚拟语⽓的倒装形式。
31.as if表⽰不可能发⽣的事情时⽤虚拟语⽓。
32.第⼀个had是过去完成时，第⼆个had表⽰“有”。
33.otherwise经常可以搭配虚拟语⽓，表⽰与过去事实相反。
34.当insist表⽰“坚持认为”时不⽤虚拟形式。
35.wish后⾯⽤虚拟语⽓，表⽰与过去事实相反⽤过去完成时。
36.but的并列句表⽰真实情况，不⽤虚拟语⽓。
37.wish后⾯⽤虚拟语⽓，表⽰与过去事实相反⽤过去完成时。
38.当insist表⽰“坚持要求”时从句⽤虚拟形式。
39.表⽰与过去事实相反，从句⽤过去完成时。