问题
单项选择题
能耗制动就是在运转的三相异步电动机脱离电源后，立即给定子绕组通入（）产生磁场，正在惯性运转的绕组中的感应电流将产生制动力矩，使电动机迅速停转。
A.直流电
B.交流电
C.高频电流
D.高压电
答案
参考答案：A
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能耗制动就是在运转的三相异步电动机脱离电源后，立即给定子绕组通入（）产生磁场，正在惯性运转的绕组中的感应电流将产生制动力矩，使电动机迅速停转。
A.直流电
B.交流电
C.高频电流
D.高压电
参考答案：A
阅读下面短文，根据短文内容在表格中的空格里填入一个最恰当的单词。每空一词。 “ Who needs a shopping mall if you have Taobao?” says Wang Lin, 28, a writer in Beijing. Taobao, China’s largest online shopping site(网站), has become an important part of Wang Lin’s life. She spends lots of money on Taobao. A growing number of Chinese Internet users like Wang Lin enjoy shopping online. Most online shoppers are students or young workers. More women shop online than men. Clothing and home use products (产品) are the most popular online. It was reported that more than 250 billion yuan was spent on online shopping last year, 80% through Taobao. Taobao means “looking for treasure” in Chinese. People can find almost everything they need on Taobao, from clothes to books, from candies to DVD players. You may question the security (安全) online shopping. Wang Lin said, “It is very safe and convenient (便利). Unless you receive the products from the sellers and are satisfied with them, the shop owner will not get the money. You can also get your money back if you want to return the product.” Taobao: China’s 小题1: online shopping center
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