问题描述：
问个英语问题 The ratio of the work done by the machine
问个英语问题
The ratio of the work done by the machine ________ the work done on it is called the efficiency of the machine.
A) against B) with C) to D) for
问个英语问题
The ratio of the work done by the machine ________ the work done on it is called the efficiency of the machine.
A) against B) with C) to D) for
问题解答：
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