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 is like?”

“I’m sorry，children.” said the teacher，“Our water is getting dirtier and dirtier．That’s a problem.”
The students were having their _______ class．

A．English

B．Chinese

C．chemistry

D．maths

Miss Li was telling the children what ______ was like．

A．water

B．air

C．earth

D．weather

A boy said，“The water in the river behind my house is always _______．”

A．white

B．black

C．clean

D．clear

Most of the children _______ the boy．

A．agreed with

B．wrote to

C．heard from

D．sent for

The water in the river has colour and smell because it is getting _______．

A．more and more	B．less and less
C．cleaner and cleaner	D．dirtier and dirtier