A:if与现在事实相反 从句：be动过
主句：should(would could might)+v
例：I would certainly go if i had the came
How nice it would be if you could stay alittle longer.
If luxun were alive today ,how happy he would be
B: 与过去事实相反 从句had+过分
主句：would(should could might)+have+过分
例：If i had left little earlier I could have caught
If i hadn’t taken your adcice,i should have made a bad mistake.大错误
C:与将来事实相反 从句（1）should+v
（2）were to+v
主句：would （should could might）+v
例：If i were to do it,i should do it in different way.
We wouldn’t lose courage even if we were to fail again也许还会失败，但不能丧失勇气。
情态v,助v,be各种形式及have 各种形式,从句中把if省略，把这几种词提到句前。
（If）they had time ,they would certainly come and help us.
Had they time , they would certainly come and help us.
又例：Should it be fine,we would go out on a walk.
D:含蓄条件中的虚拟语气（1）由介词短语表示一个虚拟条件
（2）由上下文联系表示虚拟条件
例：Without liberation, we choose people would not have begun a newlife.
If we hadn”t been liberated, we choose people would not have begun a newlife.
We would have done better under more favourable condlion.
I would have written but i have been ill.
I was ill that day,other wise i would have taken part in the party.
二、宾语从句中虚拟语气 wish ,suggest order,insiste demand request
（1）与现在事实相反 过去式
（2）与过去事实相反 过去完成
（3）与将来事实相反 （should）原形 should常省略
例：I wish (I were as strong as you)
The teacher ordered that all take part in the work.
He insisted that we take up the master at the meeting.
三、it is suggested that .It is necessary (important,strange)that
It was ordered . It has been decided that .后用虚拟语气
例：It is necessary that be sent here at once.
It has been decided that the meeting should be put off till next Saturday.
四、由as if (as though)用虚拟语气
It seems as if it were spring already
He sooke time as if i were deaf(聋子)
五、in order that (so,that)动词固定may(might)+do
口语中，用can(could)+do 否定should not do
例：Let”s hand in our exrecises earlier so that the teacher may have time to correct then.
She took a taxi so that she could get there in time.
六、在what ever ,who matter what may+动词原形
例：What ever mistakes he way have he is an honestman.
I will not let you in whever you may be.
练习
1、If i___30 year younger ,i__as old as you.答案：A
A: were__shold be B:am__shall be C:was__must be D:shall be__am
2、You __your teacher if be___her.答案：B
A:may ask__is B:could ask__were C:should ask__is
3、__the telphone number,i should have rung him up.答案：D
A：if i know B:if i knew C:i had known D:had i known
4、 If the girl __her mother yesterday ,she would have asked her about the allident.事件。答案：C
A:saw B:has been C:had seen D:would see
5、Should it be find,we__for all outing(郊游)。答案：B
A；shall go B:would go C; will go D:can go
6、He suggested that the fellow she spoke __scolded( 应该被骂，责备)答案：D
A：should be B:to should C:to be D:be
7、My suggestion is that you__at the meeting on time.答案：D
A:must be B:should go C:are D:be
8、The doctor demanded that the wounded __at once答案：C
A：be operated B:should be operated C:be operated D; should operate on
9、We insisted that we __our english exercises before lunch.答案：B
A;could finish B:should finish C:finished D:had finished
10、The chairman(大会主席)ordered that the meeting__put off.答案：D
A：should B:is C: was d: be
11、The teachers love the students as if they _their own children.答案：B
A:are B;were C; be D:should be
12、It was necessary that you __to school every Sunday.答案：D
A:must come B:come C:had to come D:should come
13、It”s strange that she _the full marks(满分)答案：B
A:gains B: should gain C:has gained D; gained
14、Our school perfered 要求that every student__active in the sports meeting.答案：D
A:must be B: is C:was D;be
15、If we had taken that teacher”s advice yesterday we __now.答案：C
A:wouid not fail B:would not be failed
C;would not have failed D:will not fail
16、__worked harder ,tom would have gotten through the chinese exam.答案：B A:if he B;had he C;if tom D:if had he
17、The students requested that the teacher__them an answer.答案：C
A；gave B；gives C:give D:will give
18、If i__you ,i should join the army.答案：C
A:am B;was C:were D：be
19、Tom wishes that he __school yesterday.答案：A
A:had been to B: had gone to C:would go to D:should go to
