19. — Could you tell me how the sea sand comes about ? — Sea waves dash against the rock. In this way , the sea sand ___ .

___ quite well in the important exam, he came back home and smiling. [ ]

I wonder _________ or not the animal signs are kept in a fixed order.— Oh, they should be.

Mr White _______his racing bicycle by himself yesterday, but I’m not sure whether it is ready

――Did they offer us enough books?――　_____ than we had expected.