情态动词的虚拟用法
can,may,could,might,should,ought to,must,need等。留学的意义
1.情态动词＋动词原形，表示对现在或将来情况的推测。例如：
I don't know where she is;she may be in Wuhan.我不知道她在哪儿，可能在武汉。
2.情态动词＋动词现在进行时，表示对现在或将来正在进行的情况进行推测。例如：
At this moment,our teacher must be correcting our exam papers.这时，想必我们老师正在批改试卷。
3.情态动词＋动词完成时，表示对过去情况的推测。它又分以下几种：
1)may(might)have＋done sth,can(could)have＋done sth.表示对过去时间里可能发生的事情的推测，表示可能性程度由大到小依次为can,could,may,might。
否定句may(might)not have＋done sth., can(could)not have＋done sth.表示推测过去时间里不可能发生的事情。例如：
Philip may(might)/can(could)have been hurt riously in the car accident.菲利普可能在车祸中受了重伤。
干尸博物馆 Mike can't have found his car,for he came to work by bus this morning.迈克不可能找到他的车，因为他今天早上是乘公共汽车来上班的。
2)must have + done sth.,对过去时间里可能发生的事情的肯定推测，语气较强，具有"高二英语课程肯定"，"想必"的意思。例如：
The road is wet.It must have rained last night.路是湿的，昨晚一定下过雨。
3)ought to have＋done sth.,should have
done sth.表示本应该做某事，而事实上并没
有做。否定句oughtn't to have done sth.,shouldn't have done sth.,表示本不该做某事但却做了。例如：
You ought to(should)have been more careful in this experiment.你当时在做试验时应该
更仔细点。
He ought not to(shouldn't)have thrown the old clothes away.他不该把旧衣服扔了。maxx(事实上已经扔了。)
4)needn't have＋done sth.表示本没有必要做某事，但却做了。例如：
I dresd very warmly for the trip,but I needn't have done so.The weather was hot.这次旅行，我穿得衣服较多，其实没有必要。那时天很热。
4.情态动词＋动词的现在完成进行时，表示对过去一直在做的事情的推测。例如：
Your mother must have been looking for you.你妈妈一定一直在找你。
2.非真实条件句
1）时态：可以表示过去，现在和将来的情况。它的基本特点是时态退后。least
a. 同现在事实相反的假设。
句型 ： 条件从句 主句
一般过去时 should/would/could/might+动词原形
If they were here, they would help you.
grit
b. 表示于过去事实相反的假设。
句型： 条件从句 主句
过去完成时 should/would/could/might have+ 过去分词
If she had worked harder, she would have succeeded.
The rice would not have been burnt if you had been more careful.
If my lawyer had been here last Saturday, he would have prevented me from going.
If he had come yesterday, I should / would have told him about it.
含义：He did not come yesterday, so I did not tell him about it.
If he had not been ill and misd many class, he would have made greater progress.
含义： He was ill and misd many lessons, so he did not make greater progress.
干戈载戢 c. 表示对将来的假想
句型： 条件从句怀疑 主句
一般过去时/were+ 不定式/should+ 动词原形 should/would/could/might+ 动词原形
If you succeeded, everything would be all right.
go to sleep If you should succeed, everything would be all right.fibc
If you were to succeed, everything would be all right
