IOG由以下几种系统组成（）。
A、FMS
B、DCS
C、MCS
D、SPS
参考答案：A, B, C, D
22. Dr. Frank failed many times but he finally_______to find a successful way to solve the problem.
A．broke off
B．broke up
C．broke down
D．broke through
家政服务员应如何采买蔬菜？
