要建立一个约束，保证用户表（user）中的年龄（age）必须在16岁以上，下面语句正确的是（）
Alter table user add check（age＞16）
B. Alter table user add default 16 for age
C. Alter table user add unique（age＞16）
D. Alter table user add default 16
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what is milestone for 12-months baby（）
A. pulls to stand
B. beginning to walk alone
C. scribbles on paper
D. immature pincher, feeds self
E. beginning to walk alone
About the description of the Denver Development Screen Test, which one is CORRECT（）
A. DDST used by general pediatricians
B. used in children from birth to 6 years of age
C. have four domains: personal-social, fine motor-adaptive, language and gross motor
D. All of the above
E. All of the above
在SQL中，创建基本表用（）命令
A. Create schema
B. Create table
Create index
D. Create view
Prices of daily goods______through a computer can be lower than store prices（）
A. are bought
B. been bought
C. bought
D. buying
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