题型:问答题 简答题 若正四面体SABC的面ABC内有一动点P到平面SAB、平面SBC、平面SCA的距离依次成等差数列,则点P在平面ABC内的轨迹是A.一条线段 B.一个点 C.一段圆弧 D.抛物线的一段 查看答案
题型:问答题 简答题 – “Have you moved into the new flat?”“Not yet. The room ________.”has been painted B. is painted C. paints D. is being painted 查看答案