【简答题】已知 E 、 F 、 G 、 H 分别是空间四边形 ABCD 的边 AB 、 BC 、 CD 、 DA 的中点. (1)用向量法证明 E 、 F 、 G 、 H 四点共面; (2)用向量法证明: BD ∥平面 EFGH ; (3)设 M 是 EG 和 FH 的交点, 求证:对空间任一点 O ,有 .
【简答题】阅读理解 The Ivy League is an athletic conference comprising eight private institutions of higher education in the Northeastern United States.The term is most commonly used to refer to those eight schools...
【判断题】The writer thinks that the foreigners entitled "Chinese scholars"understand the treasure of civilization contained in the higher classical Chinese in Chinese literature.