80% of China's population are farmers as is well-known.这是一个错句,在挑选答案时,请先动一动脑筋

应该是are改为is population的固定用法
如But counting the world's third largest population -- about three hundred nine million by current estimates -- is no easy job.
Over 75 percent of the overall affected population lives in the provinces of Sindh and Punjab.
（有道词典权威例句）你说的不错，但有人自称翻译专家，却连这个基本问题都搞不清楚，不过你解释的不够清楚，population是不可数名词，不管前面是80%还是20%，动词都用单数形式，最佳答案给你