Water can _______ rocks after a long time, even though the rock is harder.

In a () boiler the water flows through the inside of the tubes while the hotgases pass round the outside

A.water-tube

B.fire-tube

C.exhaust gas

A.Water can be used only once.

B.Used water can be recycled.

C.Recycled water is unfit for drinking.

D.Only rain water is drinkable.

A.depriving of

B.depriving

C.deprived of

D.deprived

A．rain can become water

B．snow can become water

C．Ice can become water

D．Ice can become rain

We can utilize water for producing electric power.

A．embrace

B．emerge

C．emphasize

D．employ

A．Man can catch water life in rivers.

B．The rivers can be used to raise plants.

C．Many kinds of water sports can be held.

D．People can get energy from the rivers.

A.one can

B.one cannot

C.can one

D.cannot one

A．these

B．some

C．one