--- I’m sure I will get good marks in the final exam.

--- I believe your parents will ______ your study if you try your best.

A．be satisfied with

B．be angry with

C．be bored of

D．be worried about

系统软件中最重要的软件是( )。

A．数据库管理系统
B．工具软件
C．语言处理程序
D．操作系统