Question

虚拟语气if的三种用法

Answer 1

If引导的条件状语从句中的虚拟语气：

1、表示对过去情况的虚拟：

从句：had done

主句：would/could/might/should have done

If I had read the book,I would have told you about it.

如果我读了这本书，我就会告诉你了。

2、表示对现在情况的虚拟：

从句：would/could/might/should do

主句：动词过去式

If he studied at this school，he would know the environment around the school very much.

如果他在这所学校学习的话，他会很了解周边环境。

3、表示对将来情况的虚拟：

从句：should do/were to do

主句：would/could/might/should do

If he should go to Harvard University,he would make full use of his time.

如果他要上哈佛大学的话，他就会充分利用他的时间了。

if的用法

1、if作为连词，引导条件状语从句，表示“假如，如果”等。在复合句中如果主句用将来时，则if引导的状语从句用一般现在时。

eg:If it rains(从句) ,I will stay at home（主句）。

=I will stay at home if it rains.

He will come if you invite him.

如果你请他,他会来的。

2、主句含有情态动词 （must、may、can etc.）从句为一般现在时。

eg:If you drive too fast ,you may have an accident.

=You may have an accident if you drive too fast.