18. Politician：Each year， small businesses create more jobs than do large established businesses. Therefore， in order to reduce unemployment in the long term， we should provide incentives for starting small businesses rather than for expanding established large businesses.
Which of the following， if true， casts the most doubt on the politician's argument?
(A) In general， people employed by small businesses report higher job satisfaction than do people employed by large businesses.
(B) Among the currently unemployed are many people with sufficient job skills to perform the jobs that small businesses would create.
(C) Providing an effective incentive for starting a business generally costs significantly less than providing an effective incentive for expanding a large business.
(D) A high proportion of small businesses fail within three years of starting because of their owners' inexperience.
(E) The average large business contributes more money to politicians‘ campaign funds than the average small business does.
19. In the workplace， influenza is typically spread by infected individuals to others with whom they work in close quarters. A new medication that suppresses the symptoms of influenza therefore will actually increase the number of influenza cases， because this medication will allow people who would otherwise be home in bed to return to work while infected.
Which of the following， if true， most seriously chal-lenges the prediction?
(A) Coughing， a symptom of influenza that the new medication suppresses， is a primary mechanism in the spread of this illness.
(B) Some medications that are used to suppress symptoms of influenza are also used by many people to treat symptoms that are caused not by influenza but by other illnesses.
(C) Many workers who now remain at home when infected with influenza do so because the symptoms of influenza prevent them from per-forming their jobs effectively.
(D) Most adults who are immunized against influ-enza in order to avoid being infected are over 65 years old and retired and thus do not work outside the home.
(E) Symptoms of an illness are often the body's means of curing itself of the illness， and there-fore suppression of symptoms can prolong the illness that causes them.
20. Editorial：Critics of nuclear power complain about the allegedly serious harm that might result from continued operation of existing nuclear power plants. But such concerns do not justify closing these plants;after all， their operation has caused no more harm than that caused by pollution generated by coal-and oil-burning power plants， the most important other sources of energy.
Which of the following is an assumption on which the argument depends?
(A) Existing nuclear power plants should be closed only if it can be conclusively demonstrated that their continued operation is likely to cause harm more serious than the harm their operation has already caused.
(B) Closing existing nuclear power plants would require greatly increased reliance on coal-and oil-burning power plants.
(C) The harm that has resulted from operation of existing coal-and oil-burning power plants has been significant.
(D) The harm that a nuclear power plant is likely to cause as it continues to operate can be reliably predicted from the past history of nuclear power plants.
(E) The only harm that has resulted from operation of existing coal-and oil-burning power plants has resulted from the pollution generated by these plants.
21. Drug manufacturer： Although our company requires that patients who use our new drug also pur-chase from us nonreusable kits for weekly blood testing， the expense of those kits is an entirely necessary one： weekly blood testing must be done to monitor the drug's potential side effects， which can be very dangerous.
Which of the following， if true， most seriously weak-ens the manufacturer's argument?
(A) The expense of purchasing the blood-test kits has not prevented any patients from obtaining them or the drug.
(B) Medical laboratories can perform the blood test-ing at a lower cost to patients or their insurers than the price the manufacturer charges for the kits.
(C) A one-year supply of the drug and the weekly blood-test kits can cost patients or their insurers over $10，000.
(D) Most government and other health insurance programs will not reimburse patients for the full cost of both the drug and the blood-test kits.
(E) Patients who suffer one or more of the danger-ous side effects of the drug can incur heavy expenses for the treatment of those side effects.
参考答案： 18.D 19.A 20.D 21.B