问题
单项选择题
软启动器的（）功能用于防止离心泵停车时的“水锤效应”。
A、自由停机
B、直流制动
C、非线性软制动
D、软停机
答案
参考答案：D
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软启动器的（）功能用于防止离心泵停车时的“水锤效应”。
A、自由停机
B、直流制动
C、非线性软制动
D、软停机
参考答案：D
Helen and Sally are cousins. Helen is a writer. She lives 41 to Sally, She is 42 writing every day. She doesn’t want to talk to others when she is 43 . Her friends know her well. If they want to see her, they often 44 her first. If Helen tells them she has 45 , they will come to her house. Sally works in a 46 , She is a bank clerk. She has lots of friends and they often come to see her and talk with her. 47 Helen can’t write well when they are talking. She doesn’t know what to 48 to Sally. Now Helen is talking about it with her best friend Ruth. Ruth is 49 to help Helen. She says, “You can put a note on 50 door. It would say, ‘Nobody is at home. Please come another day.’”
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