if引导从句的三种时态讲解内容是什么？

Question

如题所述

Answer 1

1、主将从现（主句为一般将来时，从句为一般现在时）。

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

=I will stay at home if it rains.

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.

3、主句为祈使句，从句要用一般现在时态。

eg:Dont play computer games if you dont finish your homework.

其他条件句：

1、错综时间条件句

有些条件句的主句谓语和从句谓语表示的动作在时间上并不一致，这类句子称为错综时间条件句。

If you had taken my advice then,you would not be in trouble now.

如果当时听我的劝，你现在就不会有麻烦了。(if 条件句是对过去的虚拟，故用过去完成时，而主句是对现在的虚拟，故用“would+动词原形”形式）。

2、含蓄条件句

有些句子虽不含条件从句，但意思和条件句相差不多，这种句子称为“含蓄条件句”，这种句子有时候会用虚拟语气。

如: Without air (If there were notair), there would be no living things. 

But for your help (If it ha dn'tbeen for your help) I couldn't have don e it.