_______ caused the accident is still a complete mystery.
| A．What | B．That | C．How | D．Where |
----Tom, you do the cleaning after school, ________ you?
---- Me again? But I did the cleaning yesterday!
| A．do | B．don’t | C．will | D．did |
Stand over there, ___ you’ll be able to see the oil painting better.
| A．and | B．till | C．but | D．or |
Never before in China __________ so carefully concerned about the food safety.
| A．people have been | B．have people been | C．are people | D．people are |
The moment I will never forget is _____ my parents discussed my new school life with me before the new term started.
| A．that | B．which | C．when | D．where |
After the big earthquake in Chile, there were about 300 aftershocks in the nearby area, ______ over 200 were quite damaging.
| A．which | B．of which | C．during which | D．whose |