Some students are so         that they often make mistakes in their homework.

A. careful         B. carefully           C. careless

下列说法错误的是 [    ]

A. 圆柱、圆锥的底面都是圆面

B. 正方体的六个面都是正方形

C. 锥体的侧面都是三角形

D. 柱体的上、下两个面一样大