It is the interaction between people, rather than the events __ occur in their lives, __ is the main focus of social psychology.
----Dad, please open the door, it ______.----OK, dear. I am coming.
This kind of sweater______very soft.
----Have all the students known that our class will visit the factory this afternoon?----Yes. Every student______about it.
The cake ______delicious.
My father has given up smoking since he ______on.