The poor motherwhen she heard the news that her only son had been killed by the enemies.A.

问题补充：

The poor motherwhen she heard the news that her only son had been killed by the enemies.

A. broke out

B. broke down

C. broke up

D. broke off

答案：

A. broke out

(答案→)B. broke down

C. broke up

D. broke off

解析：考查短语辨析。break out（战争，火灾等）爆发；break down抛锚；击垮；break up破裂；break off打断。根据句意选B。