单项选择题

There is a delicate balance of nature ______ many square miles of ocean and vegetation and clean air are needed to maintain only a relatively few human beings.

A．where
B．in which
C．when
D．how
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单项选择题
Those who ______ will burn themselves.
A．play a fire
B．play fire
C．play the fire
D．play with fire
单项选择题
A. benefit performance is a performance for which a charitable organization has bought out at a discounted price and ______ funds by selling tickets at a full price.
A．raises
B．accumulates
C．donates
D．contributes
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