SQL语言又称为 ( )
A．结构化定义语言
B．结构化控制语言
C．结构化查询语言
D．结构化操纵语言
参考答案：C
若一组数据a1，a2，…，an的方差是5，则一组新数据2a1，2a2，…，2an的方差是[ ]
A．5
B．10
C．20
D．50
If may car more reliable, I would have driven to Lhasa instead of flying last summer.[ ]
A. was
B. had been
C. should be
D. would be
