This is my animal friend. It is white. It has____eyes and____ears. It____four legs and a____tail. It can ____and____. My animal friend is a rabbit. I like it very much.
在如图所示的几何体中,四边形ABCD是等腰梯形,AB∥CD,∠DAB=60°,FC⊥平面ABCD,AE⊥BD,CB=CD=CF.
(Ⅰ)求证:BD⊥平面AED;
(Ⅱ)求二面角F﹣BD﹣C的余弦值.
Can you ____(need/ read) the list for the old man?
下列表示图上1厘米代表实地距离30千米的比例尺,正确的是( )