My sister is very stubborn, so it is __________ to change her mind.
| A．in order |
| B．in need |
| C．in charge |
| D．in vain |
—Could I ask you a rather personal question?
--Sure,_______.
| A．pardon me | B．go ahead | C．good idea | D．forget it |
.It is warned that no one is permitted______the lab after 10:00 p.m.
| A．enter | B．to entering | C．to enter | D．entering |
______has helped to save the drowning boy is worth praising.
| A．Who | B．The one | C．Anyone | D．Whoever |
.She listened with a________expression on her face,which suggested she didn’t completely understand.
| A．puzzling | B．frightened | C．frightening | D．puzzled |
The professor gave orders to the students that the rest ______ before 5:30.
| A．be finished | B．will be finished | C．will finish | D．finish |