题干
Mary and Lily are good friends，and they love to sit by the seaside，________to each other for hours.
A：talking
B：to talk
C：having talked
D：to have talked
答案(点此获取答案解析）
A
，点集
的点
满足下列所有条件：①
；②
；③
；④
；⑤
。则
几条边的多边形 （ ）