In rencent years, China and the USA have been a lot ofof views about the same problem. A.

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A. replacements
B. transformations
C. changes
(答案→)D. exchanges
解析： 句意：近几年中美两国在相同的问题上交流了很多观点。exchange用作可数名词，意思为“交换；交流；互换”， exchanges of views交流观点。change改变或变更原有的东西或人,使之不同。replacement代替；取代；更换；transformation变化;转变;变形。