单选题 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


【正确答案】 C
【答案解析】[译文] 机器所做的工作与在机器上所用的功之比，就称为机器的效率。
[考点] 固定搭配
[解析] 题中ratio与介词to是固定搭配，the ratio of A to B的意思为“A与B之比(率) ”，故选C。