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.

DS：如果x和y是≥0的数，问3^xy次方是多少？ 条件1：5^x=11^y 条件2：3^x=9^y 请问这题答案是B吗？谢谢老师！

不明白这道题的总体积为什么是（x+2）(y+2)(z+2)而不是（x+1）(y+1)(z+1);厚度不是1吗？谢谢！

我觉得这题答案应该是A吧？∵105拆分质因数可得105=3*5*7（3个完全不同的质因数）∴x+y+z=15。怎么会是C呢？？？？

向May提问，我觉得这题情况会分得很复杂，想听下老师的思路？

想向May老师提问。这题我知道条件1单独成立，但对条件2没什么思路，只能想到穷举法，当p等于2*5,3*5,3*5,2*3,2*5,3*5时，m等于2*3,2*3,2*5,5,3,2，然后一个个除发现有的余数是1，有的余数大于1，条件2单独不成立。想问老师这个思路对吗？有没有更加简洁的思路？

不懂此题。已知有A,B,C和D共4个人；问：现在从这四个人中选出3人，是ACD的概率是多少？请详细解释，谢谢老师！

不理解第一个条件均值如何得出关于6倍数的结论，是连续7个数除7余数为5则为6的倍数，所以有一个6的倍数？

不理解第一个条件均值如何得出关于6倍数的结论，是连续7个数除7余数为5则为6的倍数，所以有一个6的倍数？

第8题的思路是以BC为底，从F向BC做垂线，跟BC交点H，FH为三角形FBC的高。然后三角形BFH跟三角形BDC相似，h：30=BF：BD，但是BF长度未知，望老师解答。

第8题的思路是以BC为底，从F向BC做垂线，跟BC交点H，FH为三角形FBC的高。然后三角形BFH跟三角形BDC相似，h：30=BF：BD，但是BF长度未知，望老师解答。