The scientists are beating their brains trying to a solution to the problem.
A. e about
B. e across
C. e out
D. e up with
网友回答
A. e about
B. e across
C. e out
(答案→)D. e up with
解析：考查词组：A. e about发生B. e across遇到C. e out出版D. e up with提出，想出，句意：科学家正绞尽脑汁找出问题的解决办法。选D。