Both bus and tree topologies are characterized by the use of multipoint (1).For the bus, all stations attach, through appropriate hardware (2) known as a tap, directly to a linear transmission medium, or bus. Full-duplex operation between the station and the tap allows data to be transmitted onto the bus and received from the(3). A transmission from any station propagates the length of the medium in both directions and can be received by all other (4). At each end of the bus is a (5) , which absorbs any signal, removing it from the bus.
空白（1）处应选择（）
A.medium
B.connection
C.token
D.resource
参考答案：A
解析：
总线型和树形拓扑结构都使用多点传输介质。对于总线来说，所有站点都通过被称为接头的硬件直接连接到线性传输介质或总线上。站和接头之间的操作允许数据发 送到总线上，也可以从总线上接收数据。任何站点发送的数据都向总线两端传播，并可以被所有其他站点接收到。在总线的两端各有一个终接器，它接收并从总线上 移去所有信号。
