键盘功能分区有_________。
A．打字键区
B．混合使用区
C．功能键区
D．编辑控制键区
参考答案：A,C,D
有下列二叉树，对此二叉树中序遍历的结果为( )。
A．BDYEACFXZ
B．DYBEAFCZX
C．ABCDEFXYZ
D．ABDYECFXZ
Peter couldn't concentrate____ what he was doing while his family were watching TV. [ ]
A. on
B. to
C. in
D. for
