10mmol/L的CaCl2中氯离子的浓度是()
A.3.5mmol/L
B.5mmol/L
C.10mmol/L
D.20mmol/L
E.40mmol/L
参考答案:D
—Can you help me clean the classroom?
—___________.
A.My pleasure
B.With pleasure
C.Never mind
D.Thanks a lot
消防水泵应保证火警后______min内启动。
A.0.5 B.3 C.5 D.10