PREP 1-16,1-21

16.   (27621-!-item-!-188;#058&003223)

Most of the world's supply of uranium currently comes from mines.  It is possible to extract uranium from seawater, but the cost of doing so is greater than the price that uranium fetches on the world market.  Therefore, until the cost of extracting uranium from seawater can somehow be reduced, this method of obtaining uranium is unlikely to be commercially viable.

Which of the following would it be most useful to determine in evaluating the argument?

(A) Whether the uranium in deposits on land is rapidly being depleted

(B) Whether most uranium is used near where it is mined

(C) Whether there are any technological advances that show promise of reducing the cost of extracting uranium from seawater

(D) Whether the total amount of uranium in seawater is significantly greater than the total amount of uranium on land

(E) Whether uranium can be extracted from freshwater at a cost similar to the cost of extracting it from seawater

不明白为什么选a?

21.   (28551-!-item-!-188;#058&003690)

Traces of cultivated emmer wheat have been found among the earliest agricultural remains of many archaeological sites in Europe and Asia.  The only place where the wild form of emmer wheat has been found growing is a relatively narrow strip of southwest Asia.  Since the oldest remains of cultivated emmer wheat yet found are from village sites in the same narrow strip, it is clear that emmer wheat was first domesticated somewhere in that strip.

Which of the following, if true, most strengthens the argument?

(A) The present-day distribution of another wild wheat, einkorn, which was also domesticated early in the development of agriculture, covers a much larger area of southwest Asia.

(B) Modern experiments show that wild emmer wheat can easily be domesticated so as to yield nearly as well as traditionally domestic strains.

(C) At the time when emmer wheat was first cultivated, it was the most nutritious of all the varieties of grain that were then cultivated.

(D) In the region containing the strip where wild emmer wheat has been found, climatic conditions have changed very little since before the development of agriculture.

(E) It is very difficult, without genetic testing, to differentiate the wild form of emmer wheat from a closely related wild wheat that also grows in southwest Asia.

不明白为什么选d?

请nn指教！

Most of the world's supply of uranium currently comes from mines.  It is possible to extract uranium from seawater, but the cost of doing so is greater than the price that uranium fetches on the world market.  Therefore, until the cost of extracting uranium from seawater can somehow be reduced, this method of obtaining uranium is unlikely to be commercially viable.

Which of the following would it be most useful to determine in evaluating the argument?

(A) Whether the uranium in deposits on land is rapidly being depleted

(B) Whether most uranium is used near where it is mined

(C) Whether there are any technological advances that show promise of reducing the cost of extracting uranium from seawater

(D) Whether the total amount of uranium in seawater is significantly greater than the total amount of uranium on land

(E) Whether uranium can be extracted from freshwater at a cost similar to the cost of extracting it from seawater

这一题的argument 是Therefore, until the cost of extracting uranium from seawater can somehow be reduced, this method of obtaining uranium is unlikely to be commercially viable.

B是无关选项，题目中没有提到地理位置。

C是迷惑选项，但是C也是无关的，Argument说了只有降低成本才能使这种方法可行，而C说什么新技术可能降低成本。新技术能不能降低成本根本不能动摇或者证明这个Argument。

D也是无关，没有人关心海水里的uranium多还是土地上的多。

E典型的无关选项，注意结论里是this method (extracting uranium from seawater).就是说如果从淡水里提U比海水便宜，这个项目没有商业价值。可是即使比海水贵，从海水提取U的成本大于市场价，还是没有商业价值。

第2题用排除法。

B，C，E很容易排除。B是比W和S的产量，明显无关。C说明W的营养价值，更无关。E说区别两个野生的W，跟结论完全没有一点联系。

现在比较A和D，A说另一种野生的W大量分布于西南亚，这并不能加强结论，故排除。

D说这个地方气候一直没变，就表示这个地方现在能种的以前也能种，现在种的活的以前多半也活，那就很能说明这地方很可能在千年前首度出现人工种W。其实对D取非可以削弱结论。但是对其他4个取非毫无意义。