【正文】
is a (13)_________problem.David:You39。s getting warmer?David:Well, I39。m afraid it is. And at sometime in the future, the ice may melt pletely. Then it39。s climate seems to be getting warmer.Interviewer:We39。ve seen a lot of (4) of that, haven39。s possible that the sea could rise and 6 cities like New York and Shanghai could disappear under water.John:It sounds very (7) .David:I couldn39。ll do my best! It39。re (14)_________right. Carbon dioxide is the gas that does most ( 15)_________to the atmosphere. But we have a problem with trees too. You see, trees give out ( 16 )_________ and ( 17)___________ carbon dioxide. So they39。s a terrible ( 19 )___________.David:Yes, and another problem is all the ( 20 )______that we produce. We burn a lot of garbage, and once again, the gases pollute the atmosphere. The situation couldn39。t think it39。d better ________(stay) at home and ________ (do) your homework.39。t have time ________ a rest. (to have)39。t know whether and when ________ Shanghai in two days. (leave) is not sure how ________ out the maths problem. (work)Ex21. Don39。(prevent……from)2. 聽到孩子的話,他們猛然意識到實際上國王沒穿衣服。(as a result)。s difficult to breathe and the dust makes me ill. So if you want to go out, you39。ve ever been in. You just had to hope you39。(be caught)4. 困在了沙漠之中,于成純只能希望自己能活下來。m afraid they would not allow him ________ here.A. to smoke B. smoking C. smokes D. smoke5. Mother told me ________ the water before I drank it.A. boiling B. boiled C. boil D. to boil6. On my way home, I stopped _______ some food.A. buy B. to buy C. buying D. bought7. John was made _______ the car for a week as a punishment.A. to wash B. washing C. wash D