计算机系统中最靠近硬件的一层系统软件是（）。

（）可提供远程通信服务。

在通信专业中，描述调制模式的缩写词PSK的英文全称是（），“帧”通常翻译为英文是（）。

We did not foresee the powerful social networking side of the（）and its rapidly growing impact on our society.

All data are stored in stacked semiconductor dynamic RAM memory boards; the information recorded，the（）rate，and the order in which the data are stored differ.

Circuit Switching is problematic because data communications is（），that is， it is typically dominated by short bursts of activity with long periods of（）.