The verb not conjugated

[christianxxxa]

Hi,
I was reading a book and found an interesting grammar construction, I'm talking about these 2 sentences:

It was imperative that he stay awake.

They couldn't track down the are dealer to demand that he return what he'd stolen.

Why is it good like that? What is this grammatical construction called?

Thanks

[Alan]

Yes, it is quite correct.

This invariable form of the verb (used after constructions such as 'require that', 'order that', or 'is necessary/vital that') is called the present subjunctive.