三相鼠笼式异步电动机采用降压启动的目的是（）。
A.增大启动转矩
B.提高功率因数
C.减小启动电流
D.增大转速
参考答案：C
Sandy didn't tell her parents that she was going home because she wanted to give them a _______. [ ]
A. gift
B. call
C. surprise
D. note
以下属于急性胎儿窘迫临床表现的是()
A．胎心音120次/分
B．胎心音>160次/分
C．胎动频繁
D．胎动减弱
E．头先露羊水中混有胎粪
