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.

这一题，主要区别在于by trying to与in trying to，为何in trying to好与 by呢？ 还有一个区别是划线最后的have had to与have themselves to之间的区别，为何这里不能用have themselves to呢？尤其是在划线前面已经出现了have themselves to的情况下？

没思路，不知道结合条件一及条件二如何得出X1的值...脑子不好使！

只能做到50的阶乘，乘以2的50次方，再加1 的结果 但是后面怎么思考就不清楚了，遇到这种题该如何去做，有什么直接的方法吗？

请May老师帮忙梳理一下这个题怎么用A排列或者C组合的方法算出答案，我每次遇到这种题似乎都有点毛病，不知道应该用A还是C还是结合...

条件一不是已经表明P是C的数量的两倍吗？而原文条件也说明了P或者C其中任意一个都可能为2/3的总量，而条件一表明P=2C 则总份额就是3C。C/（P+C）=1/3，可以得出答案啊，为什么不能选？

这题我认为主要考点在if与when的连用上以及consider后面接to be或者直接接noun。如果在BC选项it无指代可以排除，ADE三个选项中为何E是最优选项呢？这里情形我认为if和when都呢说得通，而且consider后面接noun或者to be在语法上没有问题。

这题正确选项E为什么which后面没有动词而是接的不定式形式，如果这样which后面就不是完整的句子了啊？

How many positive prime numbers are less than integer n? a) 14<n<20。 b) 13<n<17

这一题C，D两个选项中明显有一点不同就是一个用了but many scientist，一个用了and mant scientist. 从句意来看的话，这句话说了A提出了一个观点，但是很多科学家怀疑，然后转折P这个人之后测出来了。虽然D选项中P做的事情用过去时优于C选项中P用完成时，但我认为C选项连词用的比D好，为什么这题D选项优于C选项？