单项选择题

A．It follows a certain cycle.
B．It affects the growth of trees.
C．It has been increasing since the Ice Age.
D．It is determined by the chemicals in the air.
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单项选择题
A．One.B．Two.C．Three.D．Four.
A．One.
B．Two.
C．Three.
D．Four.
单项选择题
In her room. B) In the restaurant. C) In the hall. D) In the kitchen.
In her room. B) In the restaurant. C) In the hall. D) In the kitchen.
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