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为何要在滑环表面上铣出沟槽？

答案

参考答案：

运行中，当滑环与碳刷滑动接触时，会产生高热反应，在滑环表面有螺旋状的沟槽，这一方面是为了增加散热面积，加强冷却，另一方面是为了改善同电刷的接触，而且也容易让电刷的粉未沿螺旋状沟槽排出。

单项选择题 A型题

阳水辨证属湿毒浸淫，其选方最佳配伍是（）

A.黄连温胆汤合温脾汤

B.越婢加术汤合银翘散

C.麻黄连翘赤小豆汤合五味消毒饮

D.疏凿饮子合己椒苈黄丸

E.舟车丸合黄连解毒汤
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问答题

Passage 2 A Different Consensus Even as the U.S. Senate debates a vast new tax and spend regime in the name of fighting climate change, a more instructive argument was taking place in Copenhagen, Denmark. Some of the world’s leading economists met earlier this month to decide how to do the most good in a world of finite resources. Scarcity is a core economic concept. There isn’t an unlimited amount of money to be spent on every problem, so choices have to be made. The question addressed by the Copenhagen Consensus Center is what investments would do the most good for the most people. The center’s blue-ribbon panel of economists, including five Nobel laureates, weighed more than 40 proposals to improve the world by spending a total of $75 billion over the next four years. What would do the most good most economically Supplements of vitamin A and zinc for malnourished children. Number two A successful outcome to the Doha Round of global flee-trade talks. Global warming mitigation It ranked 30th, or last, right behind global warming mitigation research and development. On the benefits of freer trade, it was estimated that a successful Doha Round could generate up to $113 trillion in new wealth during the 21st century, at a cost of $420 billion or less from inefficient industries going bust. Meanwhile, providing vitamin A and zinc would help some 112 million children in sub-Saharan Africa and South Asia for merely $60 million a year. The minerals would help prevent blindness and stunted growth—increasing lifetime productivity by an estimated $1 billion. Similar if not quite so bountiful returns apply to investments in iron supplements, salt iodization and deworming, all low-cost measures that the economists in Copenhagen ranked highly.
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