单项选择题

Acid fog______

A．falls down when the atmosphere is moist
B．is not as frequent as acid rain
C．often falls in the region of Manchester, England
D．is as damaging as acid rain

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热门试题

单项选择题

Why is acid rain little understood______

A．Because it is a new phenomenon
B．Because it is not frequent enough
C．Because its formation is complex
D．Because it is difficult to study it

单项选择题

From the first sentence of the passage, we learn that______

A．acid rain has caused air pollution
B．acid rain has caused widespread environmental damage
C．acid, rain has become a much studied subject
D．acid rain travels in all directions before it rains down