which one of the following statements, if true, most seriously weakens the argument?

　　(a) no female cats have been known to contract disease x, which is a subtype of disease y.

　　(b) many male cats who contract disease x also contract disease z, the cause of which is unknown.

　　(c) the interstitial nuclei of female cats who contact disease x are larger than those of female cats who do not contract disease x.

　　(d) of 1,000 autopsies on male cats who did not contract disease x, 5 revealed interstitial nuclei larger than those of the average male cat.

　　(e) the hypothalamus is known not to be causally linked to disease y, and disease x is a subtype of disease y.

　　25. there should be a greater use of gasohol. gasohol is a mixture of alcohol and gasoline, and has a higher octane rating and fewer carbon monoxide emissions than straight gasoline. burning gasohol adds no more carbon dioxide to the atmosphere than plants remove by photosynthesis.

　　each of the following, if true, strengthens the argument above except:

　　(a) cars run less well on gasoline than they do on gasohol.

　　(b) since less gasoline is needed with the use of gasohol, an energy shortage is less likely.

　　(c) cars burn on the average slightly more gasohol per kilometer than they do gasoline.

　　(d) gasohol is cheaper to produce and hence costs less at the pump than gasoline.

　　(e) burning gasoline adds more carbon dioxide to the atmosphere than plants can remove.

　　26. barnes: the two newest employees at this company have salaries that are too high for the simple tasks normally assigned to new employees and duties that are too complex for inexperienced workers. hence, the salaries and the complexity of the duties of these two newest employees should be reduced.

　　which one of the following is an assumption on which barnes's argument depends?

　　(a) the duties of the two newest employees are not less complex than any others in the company.

　　(b) it is because of the complex duties assigned that the two newest employees are being paid more than is usually paid to newly hired employees.

　　(c) the two newest employees are not experienced at their occupations.

　　(d) barnes was not hired at a higher-than-average starting salary. ;2hotV3nQ'"S;rT[ 本_资_料_来_源_于_贵_州_学_习_网 外语园地GMAT Http://wwW.gzU521.coM );2hotV3nQ'"S;rT

　　(e) the salaries of the two newest are no higher than the salaries that other companies pay for workers with a similar level of experience.

　　27. these days, drug companies and health professionals alike are focusing their attention on cholesterol in the blood. the more cholesterol we have in our blood, the higher the risk that we shall die of a heart attack. the issue is pertinent since heart disease kills more north americans every year than any other single cause. at least three factors——smoking, drinking, and exercise-can each influence levels of the cholesterol in the blood.

　　which one of the following can be properly concluded from the passage?

　　(a) if a person has low blood cholesterol, then that person's risk of fatal heart disease is low.

　　(b) smoking in moderation can entail as great a risk of fatal heart disease as does heavy smoking.

　　(c) a high-cholesterol diet is the principal cause of death in north america.

　　(d) the only way that smoking increases one's risk of fatal heart disease is by influencing the levels of cholesterol in the blood.

　　(e) the risk of fatal heart disease can be altered by certain changes in lifestyle.

　　28. ordinary mountain sickness, a common condition among mountain climbers, and one from which most people can recover, is caused by the characteristic shortage of oxygen in the atmosphere at high altitudes. cerebral edema, a rarer disruption of blood circulation in the brain that quickly becomes life-threatening if not correctly treated from its onset, can also be caused by a shortage of oxygen. since the symptoms of cerebral edema resemble those of ordinary mountain sickness, cerebral edema is especially dangerous at high altitudes.

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