题1：网络协议是计算机网络和分布系统中互相通信的(21)间交换信息时必须遵守的规则的集合。协议的关键成分中(22)是数据和控制信息的结构或格式；(23)是用于协调和进行差错处理的控制信息；定时是对事件实现顺序的详细说明，而网络体系结构则是(24)。

 题2：CMM是软件能力成熟度模型，它包含5个级别，其中KPA——定量软件过程属于(25)级别。

(159)

(158)

(157)

For each blank, choose the best answer from the four choices and write down on the answer sheet.

(71)is a one-way function that takes an arbitrarily long piece of plaintext and from it computes a fixed-length bit string.

(72)is a protocol that most USENET machines now use it to allow news articles to propagate from one machine to another over a reliable connection.

(73)is an approach preferred by cable TV providers. In this solution the fiber terminates at an optoelectrical converter and the final segment is a shared coaxial cable.

(74)is a device used to connect two separate network that use different communication protocol.

(75)is a digital-to-digital polar encoding method in which the signal level is always either positive or negative.

(156)

(153)

(154)

(152)

帧中继网的虚电路建立在()

(151)