With the effects of global warming, trees their leaves much later in the year.
| A．are losing | B．have lost | C．lost | D．were losing |
There is such a problem _____ we all should _____．
| A．as; pay attention to it | B．that; attract our attention |
| C．as; pay attention to | D．that; attract our attention to it |
How long do you believe it will be _____ Chinese people land on the moon?
| A．before | B．since | C．when | D．that |
The position _____ he wants to apply is difficult to get．
| A．to which | B．for which | C．for that | D．with which |
I can hardly say which dish is best –it’s simply a（n） _____ of personal taste．
| A．affair | B．event | C．matter | D．attitude |
－The accident might not have happened had we been more careful．
－But we _____ at that time．
| A．don’t | B．didn’t | C．hadn’t | D．weren’t |