敬请大虾帮忙，逻辑难题4

jingshuijing

14. A recent survey of all auto accident victims in Dole County found that, of the severely injured drivers and front-seat passengers, 80 percent were not wearing seat belts at the time of their accidents. This indicates that, by wearing seat belts, drivers and front-seat passengers can greatly reduce their risk of being severely injured if they are in an auto accident.
The conclusion above is not properly drawn unless which of the following is true?
(A) Of all the drivers and front-seat passengers in the survey, more than 20 percent were wearing seat belts at the time of their accidents.
(B)Considerably more than 20 percent of drivers and front-seat passengers in Dole County always wear seat belts when traveling by car.
(C) More drivers and front-seat passengers in the survey than rear-seat passengers were very severely injured.
(D) More than half of the drivers and front-seat passengers in the survey were not wearing seat belts at the time of their accidents.
(E) Most of the auto accidents reported to police in Dole County do not involve any serious injury.

18. Teresa: Manned spaceflight does not have a future, since it cannot compete economically with other means of accomplishing the objectives of spaceflight.
Edward: No mode of human transportation has a better record of reliability: two accidents in twenty-five years. Thus manned spaceflight definitely has a positive future.
Which of the following is the best logical evaluation of Edward’s argument as a response to Teresa’s argument?
(A) It cites evidence that, if true, tends to disprove the evidence cited by Teresa in drawing her conclusion.
(B) It indicates a logical gap in the support that Teresa offers for her conclusion.
(C) It raises a consideration that outweighs the argument Teresa makes.
(D) It does not meet Teresa’s point because it assumes that there is no serious impediment to transporting people into space, but this was the issue raised by Teresa.
(E) It fails to respond to Teresa’s argument because it does not address the fundamental issue of whether space activities should have priority over other claims on the national budget.

18. Researchers have found that when very overweight people, who tend to have relatively low metabolic rates, lose weight primarily through dieting, their metabolisms generally remain unchanged. They will thus burn significantly fewer calories at the new weight than do people whose weight is normally at that level. Such newly thin persons will, therefore, ultimately regain weight until their body size again matches their metabolic rate.
The conclusion of the argument above depends on which of the following assumptions?
(A) Relatively few very overweight people who have dieted down to a new weight tend to continue to consume substantially fewer calories than do people whose normal weight is at that level.
(B) The metabolisms of people who are usually not overweight are much more able to vary than the metabolisms of people who have been very overweight.
(C) The amount of calories that a person usually burns in a day is determined more by the amount that is consumed that day than by the current weight of the individual.
(D) Researchers have not yet determined whether the metabolic rates of formerly very overweight individuals can be accelerated by means of chemical agents.
(E) Because of the constancy of their metabolic rates, people who are at their usual weight normally have as much difficulty gaining weight as they do losing it.
新陈代谢，卡路里都是怎么回事？

Questions 15-16 are based on the following.
Roland: The alarming fact is that 90 percent of the
people in this country now report that they know
someone who is unemployed.
Sharon: But a normal, moderate level of unemployment
is 5 percent, with 1 out of 20 workers unem-
ployed. So at any given time if a person knows
approximately 50 workers, 1 or more will very
likely be unemployed.
∧16. Sharon's argument relies on the assumption that
(A) normal levels of unemployment are rarely
exceeded
(B) unemployment is not normally concentrated in
geographically isolated segments of the population
(C) the number of people who each know someone
who is unemployed is always higher than 90%
of the population
(D) Roland is not consciously distorting the statistics
he presents
(E) knowledge that a personal acquaintance is unem-
ployed generates more fear of losing one's job
than does knowledge of unemployment
statistics