— What on earth are the police busy with?
— They have been looking into how the plane crash .
A. came out
B. came up
C. came down
D. came about
网友回答
A. came out
B. came up
C. came down
(答案→)D. came about
解析：考查动词短语辨析。句意：--警察到底在忙些什么？--他们一直在调查飞机失事发生的原因。A出版；B走近，被提到，即将发生；C下降，下来；D发生。e about常与how连用。故选D。