救生专用配电箱电量耗尽后充电时间为（）小时。
A.5.0
B.10.0
C.15.0
D.20.0
参考答案：B
_____ a reply, he decided to write again.
A．Not receiving
B．Receiving not
C．Not having received
D．Having not received
乳胶凝集法测抗链"O"，正常参考值是（）
A.<500U
B.<600U
C.<800U
D.<900U
E.<1000U
