第6题: [单项选择]数据库管理系统DBMS中用来定义模式、内模式和外模式的语言为( )。 A. C B. Basic C. DDL D. DML 参考答案:C 答案解析:[解析] 数据定义语言(Data Definition Language, DDL)负责数据的模式定义与数据的物理存取构建;数据操纵语言(Data Manipulation Language, DML
第15题: [单项选择]According to the author. Americans' cultural blindness and linguistic ignorance will ______. A. affect their image in the new era B. Cut themselves off from the outside world C. limit their role in world affairs D. weaken the position of the US dollar 参考答案:C 答案解析:由句子"American dollars no longer...proper role in the world is changing."和"we want to have a hand...it