总线拓扑结构的优点是：
参考答案：
所需要的电缆数量少；简单又是无源工作，有较高的可靠性；易于扩充增加或减少用户比较方便。
At the meeting, they sat very ________ and had a ________ talk, but I didn't know what they were
talking about. [ ]
A. close; close
B. closely; close
C. close; closely
D. closely; closely
变压器重瓦斯保护动作跳闸时如何处理？
