阅读理解。 The students were having their chemistry class. Miss Li was telling the children what water was like. After that, she asked her students, 'What's water?' No one spoke for a few minutes. Miss Li asked again, 'Why don't you answer my question ? Didn't I tell you what water was like?' Just then a boy put up his hand and said , 'Miss Li, you told us that water has no colour or smell. But where to find such kind of water ? The water in the river behind my house is always black and it has a bad smell .' Most of the children agreed with him . 'I'm sorry, children,' said the teacher, 'Our water is getting dirtier and dirtier. That's a problem.' 1. The students were having their _______ class. [     ] A. English B. Chinese C. chemistry D. maths 2. Miss Li was telling the children what _______ was like. [     ] A. water B. air C. earth D. weather 3. A boy said, 'The water in the river behind my house is always _______.' [     ] A. white B. black C. clean D. clear 4. Most of the children _______ the boy. [     ] A. agreed with B. wrote to C. heard from D. sent for 5. The water in the river has colour and smell because it getting _______. [     ] A. more and more B. less and less C. cleaner and cleaner D. dirtier and dirtier