陆旭老师，我有一些做过的assumption题目取非的句子搞不清，你能帮忙看下吗(不说这道题目的解题思路，单纯就是取非问题，特别是双重否定或者从句里面有否定词） 1.No part of a person’s brain that is damaged by a stroke ever recovers.---> some part of a person's brain that is damaged by a stroke ever recovers. 2.Impairment of linguistic capabilities does not occur in people who have not suffered any damage to any language center of the brain.这个句子我不太会取非，正过来说这个句子就是Impairment of linguistic capabilities occurs in people who have suffered any damage to any language center of the brain.那么我取非是Impairment of linguistic capabilities occurs in people who have not suffered any damage to any language center of the brain. 3.If there are language centers on the left side of the brain, any serious stroke affecting that side of the brain damages at least one of them. 取非If there are language centers on the left side of the brain, any serious stroke affecting that side of the brain damages nothing of them. 4.这题出现两个not The collection fee will not significantly affect the purchasing power of most residents, even if their households do not reduce the amount of trash they put out. 我取非直接去前面的not: The collection fee will significantly affect the purchasing power of most residents, even if their households do not reduce the amount of trash they put out. 5.这个也差不多 Not all steel producers were unaffected by country A’s newly imposed tariffs. 我取非All steel producers were unaffected bycountry A’s newly imposed tariffs. 6.There are no plants native to western Africa that, if domesticated, could serve as staple food crops. 这个if domesticated是不是可以不管，直接改成There are some plants native to western Africa that, if domesticated, could serve as staple food crops.

请问这道题c选项为什么不能用过去完成式？之前的“had installed”不也是过去完成式吗...怎么判断什么时候用过去完成时什么时候用现在完成时什么时间用一般过去时啊？

请问这道题e选项“that”表示了什么？

请问在这道题里面 to do和doing的区别是什么？

请问这道题为什么不可以用过去完成时？“its trunk”里面的its会不会被当成是aquatic animal而不是大象？“with”之后是不可以接整句吗？

请问这道题b、c为什么不对

请问这道题e选项错在哪里？

请问这道题为什么不能选e？

请问为什么c不对？that of是什么意思？

请问in which 和 where的区别是什么？哪个能指代抽象地点，哪个是实际地点？

D选项错的原因之一是说不应该用that they participate 请问这个错在哪里了？