在Rt△ABC中，∠C=90°，AC=12，BC=5，以点A为圆心作⊙A，要使B、C两点中的一点在圆外，另一点在圆内，那么⊙A的半径长r的取值范围为____ 

在一次物理兴趣小组的活动中，小丽用天平．水．空酒瓶与几个同学一起来测量某种油的密度。他们首先测出空酒瓶的质量为300克，装满水后测得总质量为900克。然后将水倒净，装满油测得总质量为810克，那么这种油的密度是多少？

图中甲表示的地形部位是（　　）

   When Bill is very young, he loves picture. His mother often draws some for him on old pieces of paper. She is very bad at drawing, but bill likes her pictures and always wants more. Then, when he is a little older, Bill’s mother gives him some pencils and a drawing book, and he begins drawing pictures, too. But they are never good .When Bill is five years old, his mother gives him a small blackboard and some pieces of a baby on the blackboard, he draws lines(线条) and rubs(擦) them out too for ten minutes , but when he looks at his picture , he is not happy. “Well”, he says at last(最后) to his mother, “I’ll put a tail(尾巴) on it and make it a monkey.”