Question

虚拟语气

Answer 1

分类: 外语/出国
问题描述:

If her pains had been caused by a heart attack and not by panic, she would probably have been operated on in the hospital.

这里为什么要用had been caused，而不用 had caused?

He insisted that the meeting be put off till next Monday.

这里为什么要用be put off，而不用put off?为什么加be,根据是什么？

I wish man could build a nest which is as good as one built by birds.

这里为什么要用could build, 而不用could built? wish 后面不是要用动词过去式表示未发生的动作吗？

解析:

这三个句子都是虚拟语气。

1题 是与过去事实相反的虚拟语气，其结构形式为：条件句用...had done 结构（即过去完成时），主句用would_+have+done结构。由于条件句中 pains 和 cause 属于被动关系，当然只能用had been caused了。

2题 是insist+that 从句（从句用should+动词原形的虚拟语气，should 可省略）结构句型。the meeting 与put off(推迟）属于被动关系，所以只能用be put off

3题 是与现在事实相反的虚拟语气，其结构形式为：wish+that从句（从句用could/would/should...+动词原形）。在这里could是情态动词，当然其后用动词原形了