题目

如图，P为⊙O外一点，PA切⊙O于点A，且OP=5，PA=4，则sin∠APO等于 A.            B.            C.            D.  答案：B解析:连接AD，∵PA切⊙O于点A∴OA⊥AP,根据勾股定理得AO=,∴sin∠APO=.故选B. You said boys were cleverer than girls. That is _____ I disagree. [     ]A. whatB. where C. which D. why