用值域的概念来定义关系,关系是属性值域笛卡尔积的一个 ______ 。
参考答案:子集
解析:
[分析]: 用值域的概念来定义关系,关系就是属性值域进行笛卡尔积的一个子集。
根据给出的拼音写汉字,并解释成语。
(1)tì( )泗横流:_________________________
(2)重dǎo( )覆zhé( ):________________
______ the money shortage, many small companies closed down. [ ]
A. As a result of
B. As a result from
C. Resulted in
D. As a result