大力神赫拉克勒斯为什么要救普罗米修斯?
My grandfather began to use the computer in his ____(六十多岁).
(Ⅰ)求证:异面直线A1D与BC互相垂直;
(Ⅱ)求二面角(钝角)D﹣A1C﹣A的余弦值.
罗马为了取得地中海霸权,曾经和谁展开长期争霸( )