英语填空 为什么?用了什么语法

题目

英语填空 为什么?用了什么语法
1,You need not(wake)_____me up.I don't have to go to work today.
2,If you had listened carefully in class ,you (know)_____how to do this problem now.
3,You need not (write)____such a long report,because the boss has no time to read it.

答案

1,wake 因为need后面接动词原形
2,would have known因为有从句if知该句为过去完成时的虚拟语态,故从句必须用would表示虚拟
3,write