He waited with his companion_________the rescuers came, and then helped them carry her back down the mountain.
| A．when | B．until | C．unless | D．while |
Mr. and Mrs Scott prefer a trip in a small town to in so large a city as New York.
| A．this | B．one | C．it | D．that |
一Is there any possible way to help them get rid of such a bad habit?
一To tell the truth, it’s very hard．But we on this problem．
| A．worked | B．had worked | C．are working | D．had been working |
When it air pollution, Beijing faces the three “C” s，cars，coal and construction，which lead to Beijing's thick air pollution．
| A．refers to | B．comes to | C．happens to | D．speaks to |
Once education is made free，many children who have dropped out of school .
| A．will come back | B．came back | C．have come back | D．had come back |
When I lived with my roommates in the university, we often talk into the night
| A．might | B．could | C．should | D．would |