单项选择题


Questions 22 to 25 are based on the conversation you have just heard.

A．For almost a thousand years.
B．For a few decades.
C．For a century.
D．For several years.
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单项选择题
A．By filtering sea water.B．By treating sea water with chemicals.C．By taking salt out of sea water.D．By drying up sea water.
A．By filtering sea water.
B．By treating sea water with chemicals.
C．By taking salt out of sea water.
D．By drying up sea water.
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