搜题请搜索小程序“爱下问搜题”
问题 单项选择题

对于额定频率为50Hz，时间常数标准值为45ms的高压断路器的额定短路关合电流等于额定短路开断电流交流分量有效值的（）。

A.1.5倍

B.2倍

C.2.5倍

D.3倍

答案

参考答案：C

问答题 简答题

如何处理刮板输送机底槽积聚的瓦斯？
查看答案
单项选择题

Which of the following would be best to help prepare a preschool-aged child for an injection（）

A. Having an older child explain that shots do not hurt.

B. Helping the child to imagine she is in a different place.

C. Giving the child a play syringe and a bandage to give a doll injections.

D. Giving the child a pounding board to encourage expressions of anger.
查看答案