问题
选择题
--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
答案：D
考查短语辨析。come out 开花，出版，come up 走近，上来，被提出，come down 降低，下来，come about 产生，发生.答语的意思为：他们在一直调查飞机坠毁是怎么发生的。所以答案选D 。