What actually the accident has not yet been determined.
A. brought out
B. brought on
C. brought about
D. brought up
网友回答
A. brought out
B. brought on
(答案→)C. brought about
D. brought up
解析：词组考查题。Bring out 出版、阐明； bring on 使成长、提高； bring about 引起、导致； bring up 抚育、呕吐 还没确定是什么引起了这次事故。 选C