【简答题】【消耗次数：1】
关系数据模型的三要素是[填空]、关系操作和完整性约束条件。
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相关题目
【简答题】
关系模型的三类完整性约束是实体完整性、参照完整性和[填空1]。
【单选题】
数据模型三要素是指（ ）。
①
数据结构、数据对象和数据共享
②
数据结构、数据操作和数据完整性约束
③
数据结构、数据操作和数据的安全控制
④
数据结构、数据操作和数据的可靠性
随机题目
【单选题】
13. When I was a teenager, my bedroom was always ____; as an adult, though, my room is always neat..
①
tidy
②
orderly
③
mess
④
untidy
【单选题】
Women have to be more ____ than men if they want to get anywhere in the business world.
①
difficult
②
ambitious
③
traditional
④
conservative
【单选题】
24. The kind-hearted woman always tries to help others, but recently she has been ____kind and generous.
①
chiefly
②
specially
③
principally
④
especially
【单选题】
When the passenger woke up, he found himself ____in a hospital ward.
①
lie
②
lay
③
lying
④
lain
【单选题】
He should get used by now ____ Chinese food.?
①
to eating ?
②
to eat ?
③
for eating ?
④
eatin?
【单选题】
2. As time went on, he found himself ____ with the toughest job she had ever taken.
①
face
②
faced
③
facing
④
to face
【单选题】
He came to the meeting ____ his serious illness.
①
inspite of
②
in spite
③
despite of
④
despite
【单选题】
Dave ____ into the house without ____ out by his parents.
①
slipped; finding
②
slips; finding
③
slips; to be found
④
slipped; being found