The classroom is so dirty. _________ we clean it?
Sorry, madam. You’d better come tomorrow because it’s _____the visiting hours.
---When do we need to pay the balance? --- ____ September 30.
The accident is reported to have occurred _____the first Sunday in February. A. atB onC. inD. to
He suddenly saw Sue _____the room. He pushed his way _____the crowd of people of getting to her.
It’s quite ____me why such things have been allowed to happen. A. forB behindC. againstD. beyond