题目

已知△ABC∽△DEF，S△ABC：S△DEF＝1：9，若BC＝1，则EF的长为（ ） A．1               B．2                C．3               D．9 答案：C 【分析】直接利用相似三角形的性质得出相似比，进而得出EF的长． 解：∵△ABC∽△DEF，S△ABC：S△DEF＝1：9， ∴＝， ∵BC＝1， ∴EF的长为：3． 故选：C．There is a big garden in the residential buildings, ____ actually has become a good place for people to meet and communicate. [     ]A. where B. in which C. which D. that