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【单选题】
设有选修计算机基础的学生关系R,选修数据库的学生关系S。求选修了计算机基础而没有选修数据库的学生,则需进行( )运算。A.
并
B.
或
C.
交
D.
差
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举一反三
【单选题】People are not allowed ______freely at the meeting and they don’t allow ______either.A．talking;
A.
26. People are not allowed ______freely at the meeting and they don’t allow ______either. A．talking; to smoke
B.
to talk; to smoke
C.
talking; smoking
D.
to talk; smoking
【单选题】Many people spoke highly of the plan at the meeting, but _______ I don’t think it is of much practical use.
A.
logically
B.
personally
C.
totally
D.
exactly
【单选题】图示某工程基础平面布置图,在施工时若保证外墙基础受力钢筋贯通穿过,现场钢筋足尺按照9m考虑,则B轴线上 分布筋的下料长度说法中正确的是( ),保护层C=40mm。
A.
有两种，短的分布筋下料长度是 5780mm ，长的分布筋下料长度是 12980mm
B.
只有一种，分布筋下料长度是 12980mm
C.
有两种，短的分布筋下料长度是 5780mm ，长的分布筋下料长度是 13130mm
D.
只有一种，分布筋下料长度是 13130mm
【简答题】I wasn't at the meeting yesterday to hear ________ other people thought about this problem. [A] which [B] who [C] what [D] that
【单选题】People are not allowed ______freely at the meeting and they don’t allow ______either.
A.
talking; to smoke
B.
to talk; to smoke
C.
talking; smoking
D.
to talk; smoking
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