、交换式集线器又称以太网(),它使用MAC地址转发分组,能够同时传输数据而无碰撞。
参考答案:交换机
I have _____ all my papers but I still can't find my notes. [ ]
A. looked through
B. looked for
C. looked after
D. looked out
治肺热咳嗽常用药对为()
A.地骨皮+秦皮
B.地骨皮+白前
C.地骨皮+桑白皮
D.射干+马勃
E.桔梗+甘草