社会主义的目标和根本原则是实现( )。
A．按需分配B．社会公平C．按劳分配D．共同富裕
参考答案：D
— Are you going to have a holiday this year?
— I'd love to. I can't wait to leave this place _____. [ ]
A. off
B. out
C. behind
D. over
抽真空珠光砂比不抽真空珠光砂的导热系数小（）倍。
A.0
B.15
C.20
D.30
