Could you help me with some math problems–Sure. That’s _______ I’m here.

It isn’t so much whether he works hard; the question is whether he works _____

— Why isn’t Cathy here yet? — She _____ to be picked up at the station. [ ]

Usually there is a blackboard on the front wall in the classroom, _________there is a slogan.

______ home yesterday afternoon, it began to rain heavily.