Both bus and tree topologies are characterized by the use of multipoint（）．For the bus，all stations attach，through appropriate hardware（）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（）．A transmission from any station propagates the length of the medium in both directions and can be received by all other（）．At each end of the bus is a（），which absorbs any signal，removing it from the bus．

A transmission from any station propagates the length of the medium in both directions and can be received by all other（）．

A．routers

B．stations

C．servers

D．switches

以下不属于原型化方法优点的是
Ⅰ．加强了开发过程中用户的参与和决策
Ⅱ．文档资料规范、完整
Ⅲ．可以接受需求的不确定性并降低风险
Ⅳ．可以缓和通信的困难
Ⅴ．提供了一个验证用户需求的环境
Ⅵ．自上而下、从粗到精进行系统开发

A．Ⅰ、Ⅱ

B．Ⅱ、Ⅲ

C．Ⅲ、Ⅴ

D．Ⅱ、Ⅵ