问题
单项选择题
对一台确定的步进电动机而言，其步距角决定于（）。
A.电源脉冲的频率
B.电源脉冲的幅值
C.电机的通电方式
D.电机的负载大小
答案
参考答案：C
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对一台确定的步进电动机而言，其步距角决定于（）。
A.电源脉冲的频率
B.电源脉冲的幅值
C.电机的通电方式
D.电机的负载大小
参考答案：C
Once, the famous scientist Einstein travelled to many places in America to give lectures. He travelled in a __26__, and soon made friends with his driver. Each time Einstein gave the lecture, his driver __27__ sat in the front row and listened to him very carefully. The __28__ lecture was given so many times that the driver learned it well enough to give it himself. One day, when Einstein was __29__ about it, he asked the driver to give the lecture for him in a small town. That evening, both Einstein and the driver went into the lecture room. __30__ there had seen Einstein before. When the driver took his place, everybody applauded (鼓掌). Then he began the lecture. __31__ it was over, the people warmly applauded. The driver turned to look at Einstein. Einstein nodded with a smile on his face. When they began to leave the lecture room, a man __32 __ them and asked the driver a very __33__ question. The c river listened carefully, then he __34__ and said the question was interesting but really quite easy. To show how easy it is. I'll ask my __35__ to answer it," said the driver.
小题4:A. spoken B. told C. said D shouted
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