IF的虚拟语气怎么表达

一、IF的虚拟语气怎么表达

if +过去时,...would/should do sth 对现实（或对将来）的虚拟语句

if +过去完成时，......would/should do sth 对过去的虚拟语句

1. (表示条件)如果 ,主句用将来时，if从句用现在时表示将来

He will come if you invite him.

如果你请他,他会来的。

2. (表示虚拟)假如,要是

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。

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) +动词原形

If they were here, they would help you.

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) 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 missed many classes, he would have made greater progress.

含义： He was ill and missed many lessons, so he did not make greater progress.

c. 表示对将来的假想

句型：条件从句主句

一般过去时 should+ 动词原形

were+ 不定式 would + 动词原形

should+ 动词原形

If you succeeded, everything would be all right.

If you should succeed, everything would be all right.

If you were to succeed, everything would be all right.

3. 是否 = whether 连接宾语从句

I wonder if she is ill.

等你真正做题的时候，通过做题就可以观察出来，二者并没有什么冲突，只不过是形式上的不同而已。

UNLESS 是除非的意思

ONCE 是一旦的意思

IF 是如果，好像的意思