J.Martin的自顶向下规划,用逐步求精分层进行,下列哪层不属于它的求精层
A. 主题数据库规划
B. 实体分析
C. 实体活动分析
D. 应用项目分析
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(He's) a timid fellow. (That's) why he (never) (dare) to protest.
A. He’s
B. That
C. never
D. dare
Because of the poor harvest, wheat prices have ______ in the last six months.
A. added
B. jumped
C. amounted
D. developed
灭菌过程必须使物品污染微生物的存活概率减少到
A. 10-2
B. 10-3
C. 10-4
D. 10-5
E. 10-6
关系S(S#,SNAME,SEX),C(C#,CNAME),SC(S#,C#)。其中S#为学生号,SNAME为学生姓名,SEX 为性别,C#为课程号,CNAME 为课程名。要查询选修“计算机”课的全体女学生姓名的SQL语句是SELECT SNAME FROM S,C,SC WHERE子句。这里 WHERE子句的内容是
A. S#=SC.S#ANDSEX='女'AND CNAME='计算机'
B. S#=SC.S#ANDC.C#=SC.C#AND CNAME='计算机'
C. SEX='女'and CNAME='计算机'
D. S#=SC.S#ANDC.C#=SC.C#AND SEX='女'AND CNAME='