题干
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
答案(点此获取答案解析）
D
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
，较为简便的方法是( )