双网单待是指可以使用两张手机卡，但同一时间只能有一张卡处于待机。
参考答案：对
小明看一本故事书，第一天看了全书的1/9，第二天看了24页，两天看了的页数与剩下页数的比是1：4，这本书共有多少页？
Class C EPIRBs are（）.
A.manually activated and operate on maritime (VHF) channels
B.automatically activated and operate on maritime (VHF) channels
C.manually operated and detected by satellite
D.automatically operated and detected by satellite
