The shocking news made me realize ________ terrible problems we would face.
| A．what | B．how | C．that | D．why |
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 |
Not until quite recently that language is closely related to culture．
| A．he realized | B．did he realize | C．had he realized | D．he did realize |