问题补充：
The computer system suddenly while he was searching for information.
A. broke down
B. broke out
C. broke up
D. broke in
答案：
(答案→)A. broke down
B. broke out
C. broke up
D. broke in
解析：句意，当他正在寻找信息的时候，电脑系统突然坏掉了。break down（机器）出故障break out（战争、火灾等）突然发生，爆发break up分裂break in打断，故选A.
