核心问题
《新英汉辞典》和《远东英汉大辞典》将 efficacy[ˈefikəsi]和 efficiency 译作“功效”“效能”。从译文看不出它们之间有没有区别。
词典解答
efficacy 的意思是“有效性(效力)(effectiveness)”。例如，the efficacy of a means, measure, remedy, drug(某种方法、措施、策略、药的效力):
The medicine has no efficacy in that disease. 这种药对那种病无效。
efficiency 的意思是“效率”，即“日常工作中所消耗的劳动量与所获得的劳动成果的比率”或“机械工作时输出能量与输入能量的比值”：
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The workers' efficiency was low. 工人的劳动效率很低。
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These machines have raised efficiency many times. (Mis) 这些机器使效率提高了好几倍。
练习题
请做下面的英语试题：
The manner in which fuel enters a diesel engine is the primary factor that affects its efficiently. (TOEFL)