单项选择题

_______ hearing is really produced in all animals by the effect of pressure is not definitely known by scientists.

A．If or not
B．Whether or not
C．have never heard of
D．had never heard of
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单项选择题
A group of scientists demanded that the federal government ____ all the studies it has founded on cloning.
A． reveal
B．revealed
C．is revealing
D．must reveal
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Most scientists agree _______ was hot for at least a time.
A．some of the moon that
B．some of the moon it
C．that some of the moon
D． while some of the moon
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