单项选择题

Doctors sometimes ______old cures when modem medicine doesn’’t work.

A．fall on
B．fall down on
C．fall back on
D．fall in upon
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单项选择题
A．makeB．printC．performD．produce
A．make
B．print
C．perform
D．produce
单项选择题
He might have been killed ______the arrival of the police.
A．except for
B．but for
C．with
D．for
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