The backpack is_____ sale_____ only fifteen yuan.
| A．on; at | B．for; in |
| C．at; for | D．on; for |
Schools don’t allow ______ answers in the exam.
| A．copy | B．to copy |
| C．copying | D．copied |
Thomas Edison is known _____inventions______ a great inventor.
| A．to, as | B．for , as |
| C．as, to | D．to, for |
An accident______ on this road last week.
| A．has been happened | B．was happened |
| C．is happened | D．happened |
Tom is often made ______for twelve hours a day by the boss.
| A．work | B．working |
| C．to work | D．to be working |
I don’ t mind _____the door.
| A．you open | B．your open |
| C．your opening | D．yours opening |