B) Testing is optional in software life cycle.
C) CASE tools can only aid in the design phase of a software life cycle.
D)A change during a later phase does not require the documentation of all
earlier phases to be updated.
（64）WhatoperationonrelationsR and S produces the relationshown below? （ ）。
{tuple│tuple∈R□tuple∈S}
A) Union B) Difference C) Intersection D) Division
（65）Which values are NOT permitted to be part of the primary key? （ ）。
A) alpha-numeric characters B) punctuation
C) special characters D) NULL
（66）There are two styles in the evolution of instruction set , that is CISC and
RISC. Which chip belongs to the CISC?（ ）。
A) SOAR B) VAX-11/780 C)CDC6600 D) IBM RTPC
（67）According to the principle of CRC calculation, given a frame-bit series
M=11100111 and the multiple-term formula, frame-bit series generated by the
CRC G=110011, then the CRC is （ ）。
A) 111101 B) 00011 C) 11010011 D) 1101001
（68）The main goals of Networkare sharing computer resources .The resources include
hardware、data and （ ）。
A) gateway B) router C) software D) server "
（69）According to covering scope , which three classes can computer network be divided ? （ ）。
A）PSN、LAN、WAN B）MAN、LAN、WAN
C）PSN、FAST Ethernet、LAN D）PSN、FAST Ethernet、MAN
(70)In HDLC Protocol , when Supervisory Frame＇s type code is ＇00 ＇. About the
following statements , which is correct .（ ）。
A）Receive Ready B）Receive not Ready C）Reject D）Selective Reject
二、论述题
论述题1
按规范设计的方法将数据库设计分为六个阶段：1 需求分析。2 概念结构设计。3 逻辑结构设计。4 数据库物理设计。5 数据库实施。6 数据库运行和维护。针对关系数据库设计的逻辑结构设计，回答下述问题：
