When it comes to gossip(流言蜚语), learn to keep your mouth shut ________ you'll avoid trouble.
| A．or | B．and | C．for | D．but |
Once air pollution in most cities, it is hard .
| A．rises; dealing with | B．arouses; to be dealt with |
| C．raises; dealt with | D．arises; to deal with |
Only when possible to settle the problem.
| A．our teacher comes will it be |
| B．does our teacher comes will it be |
| C．our teacher comes it will be |
| D．has our teacher come will it be |
Since there is no such thing as a free lunch in the world, one million people of the city decided to build their home by themselves.
| A．a; the | B．/; / | C．/; the | D．a; / |
____is known to us all is that the 2008 Olympic Games will take place in Beijing.
| A．What | B． It | C．As | D．Which |
I found many people ________ on the benches at the end of the day，chatting.
| A．sitted | B．sitting | C．seating | D．seat |