When permits for the discharge of chemicals into a waterway are issued, they are issued in terms of the number of pounds each chemical that can be discharged into the waterway per day. These figures, calculated separately for each chemical for which a permit is issued, are based on an estimate of the effect of the dilution of the chemical by the amount of water flowing through the waterway. The waterway is therefore protected against being adversely affected by chemicals discharged under the permits. ¥ÁµŽÓ_»•forum.liuxuehome.comÊÖRF[$ïD
The argument depends on the assumption that ¥ÁµŽÓ_»•forum.liuxuehome.comÊÖRF[$ïD
(A) relatively harmless chemicals do not interact with each other in the water to form harmful compounds ¥ÁµŽÓ_»•forum.liuxuehome.comÊÖRF[$ïD
(B) there is a swift flow of water in the waterway that ensures rapid dispersion of chemicals discharged ¥ÁµŽÓ_»•forum.liuxuehome.comÊÖRF[$ïD
(C) those who receive the permits do not always discharge the entire quantity of chemicals that the permits allow ¥ÁµŽÓ_»•forum.liuxuehome.comÊÖRF[$ïD
(D) the danger of chemical pollution of waterways is to be evaluated in terms of human health only and not in terms of the health of both human beings and wildlife ¥ÁµŽÓ_»•forum.liuxuehome.comÊÖRF[$ïD
这个假设题目请大牛们重点讲解,A/B我的确是没有分开的我觉得两个都是假设.答案是A.¥ÁµŽÓ_»•forum.liuxuehome.comÊÖRF[$ïD
M: A是相关选项, 与原文中的separately对应, 如果取非,不同的chemical合成新的chemical, permit的作用就不存在了, 结论中的permits --> protection就不成立. 所以A是答案. ¥ÁµŽÓ_»•forum.liuxuehome.comÊÖRF[$ïD
B的问题在于1. 和原文中的重点问题无关(见上) 2. 非必要条件,而是充分条件. 原文提到dilution, 所以chemical要被冲散,而不是聚集在某处. B是一个充分条件, 既:有A,就有dilution. 但是原文并没有提出B这种情况是唯一的办法. 既还有可能通过其它手段来解决dilution的问题. ¥ÁµŽÓ_»•forum.liuxuehome.comÊÖRF[$ïD
举一个例子: 为了节约用电, 要求不开灯或不用电器. 如果节约了用电,我们不能推出一定是没开灯或一定是没用电器¥ÁµŽÓ_»•forum.liuxuehome.comÊÖRF[$ïD

Top college graduates are having more difficulty demonstrating their superiority to prospective employers than did the top students of twenty years ago when an honors degree was distinction enough. Today’s employers are less impressed with the honors degree. Twenty years ago no more than 10 percent of a given class graduated with honors. Today, however, because of grade inflation, the honors degree goes to more than 50 percent of a graduating class, Therefore, to restore confidence in the degrees they award, colleges must take steps to control grade inflation.¥ÁµŽÓ_»•forum.liuxuehome.comÊÖRF[$ïD
Which one of the following is an assumption that, if true, would support the conclusion in the passage?¥ÁµŽÓ_»•forum.liuxuehome.comÊÖRF[$ïD
(A) Today’s students are not higher achievers than the students of twenty years ago.¥ÁµŽÓ_»•forum.liuxuehome.comÊÖRF[$ïD
(B) Awarding too many honors degrees causes colleges to inflate grades.¥ÁµŽÓ_»•forum.liuxuehome.comÊÖRF[$ïD
(C) Today’s employers rely on honors ranking in making their hiring decisions.¥ÁµŽÓ_»•forum.liuxuehome.comÊÖRF[$ïD
(D) It is not easy for students with low grades to obtain jobs.¥ÁµŽÓ_»•forum.liuxuehome.comÊÖRF[$ïD
(E) Colleges must make employers aware of the criteria used to determine who receives an honors degree.¥ÁµŽÓ_»•forum.liuxuehome.comÊÖRF[$ïD
现在的“牛人”比以前的“牛人”更难以向顾主证明其卓越，因为过去的“牛人”凭“牛人”的等级就可以了，而现在的顾主对“牛人”的等级不太感冒了。原因是现在的学生中得到“牛人”等级的很多，所以学校一定要把得到“牛人”等级的人数控制一下。如果，现在的学生果然优秀，那么更多的人得到“牛人”就是应该的，而文中认为不应该给这么多“牛人”，那假设一定是，本来不应该有这么多牛人的，所以A是假设¥ÁµŽÓ_»•forum.liuxuehome.comÊÖRF[$ïD