文件信息的逻辑块号到物理块号的变换由哪项所决定

A．逻辑结构

B．分配算法

C．物理结构

D．页表

The service life of distress signals must be not more than（）.

A.forty two months from the date of manufacture

B.thirty six months from the date of the last inspection

C.twenty four months from the date of approval

D.twelve months from the date of purchase