单项选择题

The way to stop water pollution is______.

A．to put oxygen into the river
B．to realize the serious situation clearly
C．to make the waste materials harmless
D．to make special room in the sea for our waste

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热门试题

单项选择题

Pollution in water is noticed______.

A．when poisons are poured into water
B．when a great many fish and birds die
C．when the first organisms are affected
D．as soon as the balance of nature is destroyed

单项选择题

What is the meaning of the underlined word waterproof in the third paragraph

A．Covered with water.
B．Full of water.
C．Cleaned by water.
D．Not allowing water to go through.