题干

在市场经济活动中,商品生产者总是先卖出自己的商品转化成人民币,再用人民币去购买自己需要的商品。

人民币为什么能够购买其他商品?有人认为,为提高人民的生活水平,我国应该多发行人民币。这种观点对吗?为什么?

上一题 下一题 0.0难度 选择题 更新时间:2019-11-11 11:20:38

答案(点此获取答案解析)

①人民币是由我国国家发行并强制使用的,它在市场上执行流通手段的职能,是在商品交换中起媒介作用。所以,人们持有人民币就能购买自己所需要的商品,人民币的这种职业是受国家法律保护的;②这种观点是错误的。国家有权发行人民币,但不能任意印发,它的发行量受纸币发行规律制约。如果人民币发行量超过流通中所需的实际货币量,就会引起人民币贬值。出现通货膨胀。这样不仅不能增加财富,还会影响人民生活和经济的发展。

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       A team of engineers at Harvard University has been inspired by Nature to create the first robotic fly. The mechanical fly has become a platform for a series of new high-tech systems. Designed to do what a fly does naturally, the tiny machine is the size of a fat housefly. Its mini wings allow it to stay in the air and perform controlled flight tasks.

    “It's extremely important for us to think about this as a whole system and not just the sum of a bunch of individual components (元件), ” said Robert Wood, the Harvard engineering professor who has been working on the robotic fly project for over a decade. A few years ago, his team got the go-ahead to start piecing together the components. “The added difficulty with a project like this is that actually none of those components are off the shelf and so we have to develop them all on our own,” he said.

       They engineered a series of systems to start and drive the robotic fly. “The seemingly simple system which just moves the wings has a number of interdependencies on the individual components, each of which individually has to perform well, but then has to be matched well to everything it' s connected to,” said Wood. The flight device was built into a set of power, computation, sensing and control systems. Wood says the success of the project proves that the flying robot with these tiny components can be built and manufactured.

        While this first robotic flyer is linked to a small, off-board power source, the goal is eventually to equip it with a built-in power source, so that it might someday perform data-gathering work at rescue sites, in farmers' fields or on the battlefield. “Basically it should be able to take off, land and fly around,” he said.

        Wood says the design offers a new way to study flight mechanics and control at insect-scale. Yet, the power, sensing and computation technologies on board could have much broader applications. “You can start thinking about using them to answer open scientific questions, you know, to study biology in ways that would be difficult with the animals, but using these robots instead,” he said. “So there are a lot of technologies and open interesting scientific questions that are really what drives us on a day-to-day basis.”