Some people are bad at recalling names and faces, so it's possible that they have a condition called face blindness, ______ people suddenly have trouble recognizing family members, friends or even themselves．
| A．for which | B．which |
| C．where | D．of which |
It is written clearly in the requirements that all passengers ______ check onto board 30 minutes before the plane takes off.
| A．may | B．can | C．will | D．shall |
—I failed again. I wish I _________ harder.
—But you _________.
| A．had worked; hadn’t | B．worked; don’t |
| C．had worked; didn’t | D．worked; didn’t |
Drunk driving used to occur _______, but now it is under control.
| A．generally | B．frequently | C．practically | D．gradually |
It gives his life a flying start ______ he has gone abroad for further education.
| A．what | B．when | C．that | D．how |
The experiment has_________ the possibility of the existence of any life on that planet, but it does not mean there is no life on other planets.
| A．found out | B．pointed out | C．ruled out | D．carried out |