非同步运行过程中,电网中枢纽变电所或接有重要用户的变电所的母线电压波动最低值不低于额定值的()
A.0.9
B.0.8
C.0.75
D.0.5
参考答案:C
生活中常见的下列物质属于纯净物的是[ ]
A. 冰水
B. 果汁
C.碘盐
D.食醋
I didn't know ______. Can you tell me? [ ]
A. who to speak to
B. who speak to
C. who to speak
D. who spoke