Fzh-CTC分散自律调度集中调试和平时维护时往自律机中复制程序和数据用的接口是（）。
A、串口
B、USB口
C、并口
D、COM口
参考答案：B
I’m tired out. I__________all afternoon and I don’t seem to have finished anything.
A．shopped
B．have shopped
C．had shopped
D．have been shopping
