LSAT-12-4-13，LSAT-12-4-21

13.   There are tests to detect some of the rare genetic flaws that increase the likelihood of certain diseases. If these tests are performed, then a person with a rare genetic flaw that is detected can receive the appropriate preventive treatment. Since it costs the health-care system less to prevent a disease than to treat it after it has occurred, widespread genetic screening will reduce the overall cost of health care.

The argument assumes which one of the following?

(A) The cost of treating patients who would, in the absence of screening, develop diseases that are linked to rare genetic flaws would be more than the combined costs of widespread screening and preventive treatment.

(B) Most diseases linked to rare genetic flaws are preventable.

(C) The resources allocated by hospitals to the treatment of persons with diseases linked to genetic flaws will increase once screening is widely available.

(D) Even if the genetic tests are performed, many people whose rare genetic flaws are detected will develop diseases linked to the flaws as a consequence of not receiving the appropriate preventive treatment.（A）

(E) If preventive treatment is given to patients with rare genetic flaws, additional funds will be available for treating the more common diseases.

者道题我选B，我想这个假设错误的原因是不是未扣住大结论receive the appropriate preventive treatment. 已体现B

21.   When the supply of a given resource dwindles, alternative technologies allowing the use of different resources develop, and demand for the resource that was in short supply naturally declines. Then the existing supplies of that resource satisfy whatever demand remains. Among the once-dwindling resources that are now in more than adequate supply are flint for arrowheads, trees usable for schooner masts, and good mules. Because new technologies constantly replace old ones, we can never run out of important natural resources.

Which one of the following, if true, most seriously undermines the conclusion?

(A) The masts and hulls of some sailing ships built today are still made of wood.

(B) There are considerably fewer mules today than there were 100 years ago.

(C) The cost of some new technologies is often so high that the companies developing them might actually lose money at first.

(D) Dwindling supplies of a natural resource often result in that resource’s costing more to use.（E）

(E) The biological requirements for substances like clean air and clean water are unaffected by technological changes.者道题看了原来的帖子还是不明百，麻烦大家了

13. B is not an assumption. In another word, if B is not true, the argument still holds. For example, if only 40% of the diseases are preventable, the overall cost will still be reduced, if all the other assumptions are correct (e.g. A). Therefore, reading and understanding the conclusion is very important. If the conclusion says that the costs will be reduced by huge margin, "most" in B might be assumed.

21. Did you read the conclusion carefully enough? It says technology makes it true that we never run out of natural resources. E says technology does not affect some natural resources. Break the link in the conclusion.