参考答案

正确答案：D
解析：词汇理解题。对应文中第三段，根据To promote social ties，housing complexes are opening communitycenters that are staffed 365 days a year from 11A m. to 6 p.m. by volunteers，most of whom are seniors．可知housing complex 是一对外开放的社区中心，可用排除法得出D最符合文意。complex n.联合体.