某物理接口信号线的长度不超过15m,其数据传输率在20kbps以内,则它是()标准的接口。
A.RS-232
B.RS-422
C.RS-423
D.X.21
参考答案:A
Three students were chosen to________the experiment.[ ]
A. take out
B. look out
C. carry out
D. watch out
热备份路由(HSRP)的实现方法