问题补充：
There was a big forest fire last week, but nobody knows how it.
A. took place
B. turned up
C. broke out
D. broke up
答案：
A. took place
B. turned up
(答案→)C. broke out
D. broke up
解析：句意，上周发生了一场大森林火灾，但是没有人知道它是怎样爆发的。took place 发生 turned up 出现 broke out （战争、火灾等）突然发生，爆发 broke up 分裂，根据题意，故选C。
