用一平面截下面的几何体,无法得到长方形截面的是[ ]
A.正方体
B.长方体
C.圆锥
D.圆柱
答案:C
How did they get there
A.They started to look for the subway station.
B.They Would rather drive than go by subway.
C.They went by subway because the car wasn’t working.
D.They drove so they wouldn’t have to go by subway.
不变标志是构成总体的基本条件,但并不是统计研究的对象。