The conclusion is that 这地区过去五年都产量很低都是因为这个病的关系. If there was one year when the severe symptom of the disease became obvious during any of the last five years, then the farmer could tell their plants had this disease. But they did not. So to reach the conclusion of the argument, the assumption has to be that during all 5 years when the disease harmed the grapes, the symptoms have never been severe enough for the farmer to tell.
京公网安备11010202008513号 京ICP证101109号 京ICP备12012021号
发表于 2010-12-12 00:16:50
收藏
收藏
