再求助一道lr，谢谢啦~~

4.     A work of architecture, if it is to be both inviting and functional for public use, must be unobtrusive, taking second place to the total environment. Modern architects, plagued by egoism, have violated this precept. They have let their strong personalities take over their work, producing buildings that are not functional for public use.

Which one of the statements below follows logically from the statements in the passage?

(A) Unobtrusive architecture is both inviting and functional.

(B) Modern architects who let their strong personalities take over their work produce buildings that are not unobtrusive.

(C) An architect with a strong personality cannot produce buildings that functional well for the public.

(D) A work of architecture that takes second place to the environment functions well for public use.

(E) A work of architecture cannot simultaneously express its architect’s personality and be functional for public use.

一道lsat题，好像也是feifei上的一道题吧。题干不难，正确选项是B,我选的是E

关于B 我的疑问是： 

     题干给出的关系是 both inviting and functional for public use → unobstrutive    即X→Y

      而B选项的关系是let their strong personalities take over their work → produce bulidings not functional for public use →not unobtrusive  即非X→非Y     但原命题正确并不代表否命题正确啊  所以我觉得B有问题

  关于E  如果错的话也就是express its architect's personality 不等同于strong personalities take over their work  不过因为词组意思错而错误的情况比较少  不知道各位牛牛怎么想？

A 非充分必要条件，不能反推。

B 正解。

C cannot太绝对（一般看到绝对词，基本可以判断错误选项）

D 非充分必要条件，不能反推。

E cannot太绝对。（用逻辑推也明显错）

关于B你的分析：X→Y没问题，不过题支B中的X换成了Modern architects的作品，而不是A work of architecture，而这个X2在文中联系的是have violated this precept，这里的violated 即取非，得出producing buildings that are not functional for public use即非Y，即得出X2→非Y，这里的B逻辑就是X2→非Y。（不是你先前的非X→非Y）

但是牛牛还是没有讲到 not unobtrusive的问题啊

我的意思是题干的逻辑是 both inviting and  fuctional → unobtrusive  X→Y

而B选项的逻辑就相当于 not fuctional → not "both inviting and fuctional" → not unobtrusive  Z→非X→非Y

还是不解啊~~~~？？

如你所推，X→Y自然不能得到非X→非Y,

请看题干中：“Modern architects, plagued by egoism, have violated this precept. ”去掉插入语即“Modern architects have violated this precept. ”

而(B)选项：“ Modern architects who let their strong personalities take over their work produce buildings that are not unobtrusive.”简化即“Modern architects are not unobtrusive”

题干“Modern architects have violated this precept. ”将“this precept”用“must be unobtrusive”代换，即得到B选项“Modern architects are not unobtrusive”。

因此，B为正解。

crusoecrusoe太热情了  一直以来都是你回答我的问题 

 呵呵 我的问题也多了点儿~~~~

那我就继续问啦~~  我感觉我做不来的题主要还是题意没理解透

15.   Twenty years ago the Republic of Rosinia produced nearly 100 million tons of potatoes, but last year the harvest barely reached 60 million tons. Agricultural researchers, who have failed to develop new higher yielding strains of potatoes, are to blame for this decrease, since they have been concerned only with their own research and not with the needs of Rosinia.

Which one of the following is an assumption on which the argument depends?

(A) Any current attempts by agricultural researchers to develop higher-yielding potato strains are futile.

(B) Strains of potatoes most commonly grown in Rosinia could not have produced the yields last year that they once did.

(C) Agricultural researchers often find concrete solutions to practical problems when investigating seemingly unrelated questions.

(D) Wide fluctuations in the size of the potato crop over a twenty-year period are not unusual.

(E) Agricultural research in Rosinia is funded by government grants.

答案是B  B的意思感觉有点儿绕 "commonly grown strains本不应该有去年这个产量，而这个产量以前它们也有过"  怎么起到assumption作用了呢？

17.   Samples from the floor of a rock shelter in Pennsylvania were dated by analyzing the carbon they contained. The dates assigned to samples associated with human activities formed a consistent series, beginning with the present and going back in time, a series that was correlated with the depth from which the samples came. The oldest and deepest sample was dated at 19,650 years before the present, plus or minus 2,400 years. Skeptic, viewing that date as too early and inconsistent with the accepted date of human migration into North America, suggested that the samples could have been contaminated by dissolved “old carbon” carried by percolating groundwater from nearby coal deposits.

Which one of the following considerations, if true, argues most strongly against the suggestion of the skeptics?

(A) No likely mechanism of contamination involving percolating groundwater would have affected the deeper samples from the site without affecting the uppermost sample.

(B) Not every application of the carbon-dating procedure has led to results that have been generally acceptable to scientists.

(C) There is no evidence that people were using coal for fuel at any time when the deepest layer might have been laid down.

(D) No sample in the series, when retested by the carbon-dating procedure, was assigned an earlier date than that assigned to a sample from a layer above it.

(E) No North American site besides the one in Pennsylvania has ever yielded a sample to which the carbon-dating procedure assigned a date that was comparably ancient.

   这个可以根据排除法选出答案是A

  但关于A我的疑问是： A的意思是说 渗透的地下水若污染了低层的samples则也必定会污染高层的samples

  但题干根本没涉及高层的samples有没有被污染啊，甚至都没提到高层的sanmples  这个可不可以看做无关呢？

第二题 我有点儿明白了（呵呵，自问自答）

就是说：关于怎么解释正确选项B: 既然文中说最oldest的是最deepest的，自然也就说明低层的比高层的要older  如果低高层都被污染，就体现不出这种差别了

15.   Twenty
years ago the Republic of Rosinia produced nearly 100 million tons of
potatoes, but last year the harvest barely reached 60 million tons.
Agricultural researchers, who have failed to develop new higher
yielding strains of potatoes, are to blame for this decrease, since
they have been concerned only with their own research and not with the
needs of Rosinia.

大前提关键词：100 million tons.（以前100）

小前提关键词： 60 million tons.（现在60，是减少）

假设：？（为何数量上减少导致结论的事实）

结论：Agricultural researchers are to blame for this decrease.（农学家难辞其咎）

题目问假设是啥？

(B) Strains of potatoes most commonly grown in Rosinia could not have produced the yields last year that they once did.

因为“Strains of potatoes most commonly grown have produced the yields last year that they once did.”（去年未改良品种也是这个产量，是对结论农学家难辞其咎的weaken），因此，not+weaken，便是对结论的假设。

这是典型“not + weaken”假设题。

”