lsat-1-1-8

crescent

8. Neuroscientists are making progress in discovering more about the cause of Alzheimer’s disease. Alzheimer’s disease patients suffer from dementia and sever memory loss. Autopsies performed on such patients have revealed the presence of brain lesions caused by abnormal protein deposits. Similar deposits are also found in the brains of elderly patients who do not suffer from Alzheimer’s disease. It follows that everyone who lives long enough will eventually develop Alzheimer’s disease.

Which one of the following statements, if true, most seriously undermines the conclusion that everyone who lives long enough will eventually develop Alzheimer’s disease?

(A) The lesions found in the brains of non-Alzheimer’s disease patients are far less extensive than those found in the brains of Alzheimer’s disease patients.

(B) The developing brain produces a greater number of cells than it will ever use. The extra cells are later destroyed by what biologists call “programmed cell death.”

(C) The procedure that allows scientists to discover the presence of protein deposits during an autopsy is not yet refined enough to ensure detection of the lesions in all patients.

(D) Autopsies have shown that some people lack the chemical necessary for protein deposits to cause brain lesions.

(E) Though most Alzheimer’s disease patients develop the disease when they are in their late fifties to early seventies, the frequency of patients who develop the disease in their forties is on the rise.

答案是D，我选了A，A为什么不对啊？D什么意思？

kingsoft

    原文推理：abnormal protein deposits——》the presence of brain lesions ——》Alzheimer’s disease

                      Old patients也有abnormal protein deposits

                      结论：everyone who lives long ——》Alzheimer’s disease

    问削弱结论：chemical——》protein deposits（——》the presence of brain lesions ——》Alzheimer’s diseaseAlzheimer’s disease）

     就是说，没有这种特异的chemical，即使老也不会得病——》削弱

crescent

那A为什么不对呢？
虽然都有abnormal deposits，但是一个老人，如果他不是Alzheimer patients，那么他的abnormal deposits远远少于可以致病的量，通过排除联系达到削弱的目的啊

lip00ff2002

i am not expert, but try to answer the question:

Causes:

1. Autopsies performed on such patients have revealed the presence brain lesion caused by abnormal protein deposits,

2. these patients have Alzheimer's disease

3. Old patients也有abnormal protein deposits

Effect: Everyone who lives long ——》Alzheimer’s disease

If we want to undermine the cause——》effect, we will negate the cause. So we say, autopsies have shown that some people lack the chemical necessary for protein deposits to cause brain lesions. We point out the data collected from the autopsies are wrong now. Then we undermines the conclusion.

But Option A mentions some new terms, non-Alzhemer's disease patients, and make comparision with those Alzhemer's disease patients, which is unacceptable.

Hope it works for you now.

mindfree

Agree with lipooff2002...The argument does not involve non-Alzhimer disease patient. A is irrelevant.

crescent

OK，多谢，再问一句，是不是选项里出现了new term都可视为无关选项呢？

rhod

No.

不能这么来看，首先是要看题型，比如归纳题里出现new term基本是错的。其他类型如削弱，加强，都有所谓的他因加强和削弱，他因就是new term。

我自己的体会，主要还是判断这个new term和题目中的line of reasoning是否相关.