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创新不是一蹴而就的,而是需要不断积累和突破的过程。
和平不是免费的,需要不断努力维护。
解析:意在言外,得意忘言。
Trade between two countries can be mutually beneficial, even if one of them is less efficient in the production of all commodities.
The combination problem is the most difficult aspect of panpsychism.