The students are having their chemistry (化学) class.Miss Li 1 the children what water is like.After that，she asks her students some questions.2 them is，"Boys and girls！What is water？3 you tell me？" She waits for a few minutes，but no one answers her.Then Miss Li asks again."Why don't 4 answer my question？I have told you what water is like，right？"
Then a boy puts up his hand and 5 ，"Miss Li，you tell us that water has no color and no smell (味道).But I think water 6 something that is black when I wash my hands in it."
All the students begin to laugh (笑).Miss Li laughs，too.Then another boy puts up his hand.Miss Li asks，"What do you 7 ，Wang Bing？" The boy says，"Miss Li，where can we find water that has no color and no smell？"
"Why do you say so？" Miss Li 8 ．
"9 water in the river behind my house is always black and it has a bad smell，" answers the boy.And most of the children think he is right.
"I am sorry 10 that，children，" says the teacher."Our water is getting dirtier.That is a problem.All of us must try our best (尽力) to make it clean again."
