It is demanded / necessary / a pity + that…结构中的主语从句的谓语动词要用should 加动词原形,should 可省略.

It is demanded / necessary / a pity + that…结构中的主语从句的谓语动词要用should 加动词原形,should 可省略.
It is demanded / necessary / a pity + that…结构中的主语从句的谓语动词要用should 加动词原形,should 可省略.
虚拟的时候难道都是should加动词原型吗?万一表示的是对过去的虚拟呢?
我看到有说 it is strange that he should have lost his interest in much of his research.
用的虚拟却没有用should 加动词原形.确用了should have done.
是不是对过去的虚拟就不是用should加动词原形了?那对将来的虚拟呢?