问题
问答题 简答题
请简述输油泵的工作原理是什么？
答案
参考答案：
活塞式输油泵一般由凸轮轴上的偏心轮驱动体（或杆）使活塞作往返运动，输油泵活塞在往返运动过程中，完成吸油和泵油的过程，进油口和出油口都由单向阀控制燃油的单向流动，活塞式输油泵又分为单作用和双用两种。
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请简述输油泵的工作原理是什么？
参考答案：
活塞式输油泵一般由凸轮轴上的偏心轮驱动体（或杆）使活塞作往返运动，输油泵活塞在往返运动过程中，完成吸油和泵油的过程，进油口和出油口都由单向阀控制燃油的单向流动，活塞式输油泵又分为单作用和双用两种。
Passage Two
| In the past, young people in Japan were expected to take on responsibilities to support their parents and grandparents. Now they expect to be supported well into young adulthood. The "new breed", born since the 1960s, have never known anything but richness. Youth are seen as resistant to entering society as mature adults to becoming social citizens. Once the great objective of reconstruction after the Second World War was accomplished, a new generation lost the motivating power that had united the nation together. Japan’s birth rate has been falling rapidly, partly because of the recession, and the job and financial insecurity that it has caused. In 1999, the figure was 1. 38 children per woman, the lowest ever recorded. At the same time, youth crime, although still especially low by western standards, rose to its highest level since record-keeping began 32 years ago. Likewise, the proportion of students dropping out before graduating, at 2.5% also very low by western standards, has nevertheless been rising. Entrepreneurial (企业家的) role models are few and far between. Bill Gates is often mentioned, but a foreign model can only have so much influence. The problem is that Japanese culture discourages people from revealing details of personal life, including such ordeal (考验) as starting a company. In the past, successful companies such as Honda or Hitachi provided role models of a sort. But today they have been faded by the downturn, and few others have risen to take their place. By the same reason, young people often feel isolated from their fathers who worked too hard at their jobs to establish much of a relationship with their children. "The one thing they’re sure of is that they don’t want to be like their fathers. And the girls don’t want to be with boys who are like their fathers, so the boys are sure not to be," says Professor Morishima. |
The word "it" ( Line 2, Para. 2) most probably refers to ______.
A．economic depression
B．job insecurity
C．birth rate
D．financial unsafety