The scientists are beating their brains trying to a solution to the problem.A. come about

The scientists are beating their brains trying to a solution to the problem.
A. come about
B. come across
C. come out
D. come up with

A. come aboutB. come acrossC. come out(答案→)D. come up with解析：考查词组：A. come about发生B. come across遇到C. come out出版D. come 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。

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