And in practical terms, we can define the efficiency as the ratio of the heat in to the work out.

在实际中，我们定义,效率为热与功的比值。

麻省理工公开课 - 热力学与动力学课程节选

In the meantime, I believe that the U.S. is doing quite a bit of work in terms of raising fuel efficiency standards,

同时，我相信美国在提高燃料效率标准方面做了不少事，

对全球变暖的政策 - SpeakingMax英语口语达人