对于ISL,下面哪个是正确的()?
A.ISL用在访问链路上
B.ISL用在不同厂商的交换机间
C.ISL能产生非法的以太网帧
D.ISL指交换机间的任何链路
参考答案:A
Helen hurt her leg while _____ on the playground. We had to send her to the hospital. [ ]
A. played
B. playing
C. was playing
D. is playing
桥梁支座是( )的支承部分。
A.简支梁结构
B.桥跨结构
C.桁架结构
D.刚架结构