皮皮学，免费搜题
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【单选题】
关于实体完整性规则，正确的叙述是______。A.
实体完整性规则规定关系的主码不能为空
B.
实体完整性规则规定关系的候选码不能为空
C.
实体完整性规则规定关系的主属性不能为空
D.
实体完整性规则规定关系的外码不能为空
拍照语音搜题，微信中搜索"皮皮学"使用
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皮皮学刷刷变学霸
举一反三
【单选题】Which of the following schools would admit children without reference to their academic abilities in the UK?
A.
independent schools
B.
comprehensive schools
C.
secondary schools
D.
grammar schools
【单选题】What is the other name of public schools in the UK?
A.
Independent schools.
B.
Private schools.
C.
State schools.
【单选题】What is the other name of state schools in the UK?
A.
Public schools.
B.
Private schools.
C.
Comprehensive schools.
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