程控交换机的硬件主要分为三个系统：话路系统、控制系统和（）。
参考答案：输入输出系统
He had learnd ___ such things, so he refused ___.
A．to do, being taught to
B．doing, to be taught to
C．to do, to be taught to
D．doing, being taught to
气滞血瘀多与何脏腑的生理功能相关。（）
A.肺
B.脾
C.肾
D.三焦
E.以上都不是
