III. 完形填空。(每小题1.5分，共15分)

　　根据短文内容，从A、B、C、D四个选项中选出一个能填入相应空格内的最佳答案，并把答题卡上对应题目的答案标号涂黑。

　　March 22nd is World Water Day. It started in 1993. It not only makes us think about the importance of water, but also calls on (号召) us to 39 and protect water. Today, we’re facing terrible water problems. Among them, wastewater problem is especially 40 . And the subject of World Water Day in 2017 is “wastewater”.

　　What is wastewater? It is used water. Usually, wastewater comes from homes, 41 , hospitals and so on. It is produced by different kinds of activities, including washing the machines, taking showers and using the kitchen. The rain also 42 wastewater when it is running down the street during a storm. No matter where it comes from, this kind of water is sure to have 43 harmful in it.

　　44 must we treat (处理) wastewater? Wastewater has a big influence on our life. It causes both illness for us and pollution for the environment. We must care for our environment and our own 45 .

　　How can we treat wastewater? Different kinds of wastewater need different ways of treatment. Wastewater 46 homes can be reused. Then there will be 47 wastewater. Also, factory wastewater has to be cleaned 48 it goes back to nature.

　　39. A. drink B. save C. carry D. watch

　　40. A. easy B. popular C. small D. serious

　　41. A. factories B. lakes C. rivers D. seas

　　42. A. gets back B. hands in C. changes into D. picks up

　　43. A. nothing B. something C. nobody D. somebody

　　44. A. What B. Who C. Why D. How

　　45. A. work B. interest C. health D. business

　　46. A. on B. for C. with D. from

　　47, A. less B. more C. better D. worse

　　48. A. and B. whether C. after D. before