【题目】The fire started on the second floor and it wasn't long ______ the whole building was burned down.
A. while B. when
C. after D. before
在线课程【答案】D
【解析】试题分析：考查连词 句意为：大火在第二层楼开始蔓延，不久整栋大楼就被烧毁了。it isn’t/wasn’t long before 结构意为“不久…就…”；It +be+时间段+before结构意为“...之后才... ”