Question

英语语法题（虚拟语气），求详解

1.Tom might have come to Professer Smith's lecture but he got up rather late.(为什么填but he got up rather late，可以用if he had gotten up early么）

Answer 1

当If 表虚拟语气时候，表示与过去事实相反：
If ... had done ..., ... would(might,could) have done...
从句谓语动词用had+done，主句用should/would/could/might+have+done结构。

所以这个句子如果用if从句 的话，应该是Tom might have come to school in time for the lecture if he had gotten up earlier.

might have done sth 表示本因该做某事而事实却没有做，也表示与现在事实相反。如果后面有but，则表转折，所以后面句子不用虚拟语气，而要用陈述语气，一般过去时。所以but he got up rather late也是对的。

这道题应该是个选择题，根本还是考察的虚拟语气，表示与过去事实相反：
If ... had done ..., ... would(might,could) have done...
但备选答案上没有if的正确答案，所以选择了陈述语气。

希望对你有帮助

Answer 2

一般情况系，if/when 后面不接完成时。上面的句子可以换成：Tom might have come to Professer Smith's lecture if he got up early.