---What on earth are the police busy with?-They have been looking into how the plane cr

问题补充：

---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

答案：

A. came out

B. came up

C. came down

(答案→)D. came about

解析：词义辨析。came out出现,出版,结果是came up；提出来(流行,走近,来临,上,升)；came down下来，下落； came about发生。他们一直在调查坠机事件是怎么发生的？选D。