单项选择题

This passage mainly discusses______.

A．water conservation
B．the hydrologic cycle
C．underground water
D．polluted ground water
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单项选择题
The supply of ground water is getting low because of ______.
A．conservation
B．poisonous water
C．pollution
D．population increase
单项选择题
Which of the following is TRUE about ground water
A．It comes from the oceans.
B．It depends on seasonal rain.
C．It is 95% of all water.
D．It collects under the eart
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