我国现存占地面积最大的帝王宫苑是( )。
A．颐和园B．承德避暑山庄C．拙政园D．清晖园
参考答案：B
两个变量间的线性相关关系越不密切，相关系数r值就越接近()。
A.-1
B.1
C.0
D.1或-1
While ____ in tea with that dealer, Mr. Smith had himself ____.
A．trading; ripped off
B．buying; ripping off
C．selling; ripped off
D．purchasing; rip off
