题目内容：

the history teacher told the students that World War ___ in 1914.
Ahad broken outB was broken out
C broken out Dhad been broken out

优质解答

此题选择C.背题考查的是短语 break out（爆发）,该短语无被动语态!跟据主从时态一致的原则,主句的谓语told是一般过去时态,所以从句也要用 break out的过去式 broken out !