Passage 1

When did I decide to find out about "Aunt Maggie" a. Three years ago. b. When my father died. c. About 85 years after my correspondence with her. d. When i was nineteen.

泵的厂用耗电率是指在相同的一段时间内、泵所消耗的电量与发电机所产生的电量的（）。