题目

There is a lady at my school,  61  job is to hand out call-slips (索书单) and prevent students from leaving campus  62  permission. Before today I had never seen her smile.  The other day my friends and I were eating in the cafeteria and I saw her walking around. When she came  63  (close) to us I could see that she was crying. She pulled out a tissue and quickly wiped her eyes. I thought to myself that this lady was so under-appreciated and needed  64  (recognize) for all her hard work. So I wrote a note telling her that the students appreciated everything she did and�在平面直角坐标系中，已知A（0，2），将⊙A绕原点O顺时针旋转α时，⊙A与x轴正半轴相切，若⊙A半径为1，则旋转的角度为α（0°＜α＜180°）等于 _________ ．