She hardly ever speaks English after class, for she is afraid       mistakes.

A．to making

B．to make

C．of make

D．makes

计算机系统包括( )。

A．系统硬件和系统软件

B．硬件系统和软件系统

C．主机和外部设备

D．主机、键盘、显示器和辅助存储器