题干
When he saw a wallet on the playground, he at once.
A：picked it up
B：gave it up
C：picked up it
答案(点此获取答案解析）
A
When he saw a wallet on the playground, he at once.
A：picked it up
B：gave it up
C：picked up it
切圆
于点
，割线
经过圆心
，
绕点
到
，则
的长为（ ）
