19. Spectroscopic analysis has revealed the existence of frozen nitrogen, methane, and carbon monoxide on the surface of Pluto. Such ices have a tendency to vaporize, producing an atmosphere. Since the proportion of any gas in such an atmosphere depends directly on how readily the corresponding ice vaporizes, astronomers have concluded that the components of Pluto s atmosphere are nitrogen, carbon monoxide, and methane, in order of decreasing abundance.
The astronomers argumetn relies on which one of the following assumptions?
(A) There is no more frozen nitrogen on the surface of Pluto than there is either frozen carbon monoxide or methane.
(B) Until space probes reach Pluto, direct analysis of the atmosphere is impossible.
(C) There is no frozen substance on the surface of Pluto that vaporizes more readily than methane but less readily than carbon monoxide.
(D) Nitrogen is found in the atmosphere of a planet only if nitrogen ice is found on the surface of that planet.
(E) A mixture of nitrogen, carbon monoxide, and methane is characteristic of the substances from which the Solar System formed.
20. Ann will either take a leave of absence from Technocomp and return in a year or else she will quit her job there; but she would not do either one unless she were offerend a one-year teaching fellowship at a prestigious university. Technocomp will allow her to take a leave of absence if it does not find out that she has been offered the fellowship, but not otherwise, Therefore, Ann will quit her job at Tedhnocomp only if Technocomp finds out she has been oftered the fellowship.
Which one of the following, if assumed, allows the conclusion above to be properly drawn?
(A) Technocomp will find out about Ann being offered the fellowship only if someone informs on her.
(B) The reason Ann wants the fellowship is so she can quit her job at Technocomp.
(C) Technocomp does not allow any of its employees to take a leave of absence in order to work for one of its competitors.
(D) Ann will take a leave of absence if Technocomp allows her to take a leave of absence.
(E) Ann would be offered the fellowship only if she quit her job at Technocomp.
21. If a mechanical aerator is installed in a fish pool, the water in the pool can be properly aerated. So, since John s fish pool does not have a mechanical aerator, it must be that his pool is not properly aerated. Without properly aerated water, fish cannot thrive. Therefore, any fish in John s fish pool will not thrive.
Which one of the following arguments contains an error of reasoning that is also contained in the argument above?
(A) If alum is added to pickle brine, brine can replace the water in the pickles. Therefore, since Paula does not add alum to her pickle brine, the water in the pickles cannot be replaced by brine. Unless their water is replaced with brine, pickles will not stay crisp. Thus, Paula s pickles will not stay crisp.
(B) If pectin is added to jam, the jam will gel. Without a setting agent such as pectin, jam will not ge. So in order to make his jam gel. Harry should add a setting agent such as pectin to the jam.
(C) If stored potatoes are not exposed to ethylene the potatoes will not sprout. Beets do not release ethylene. Therefore, if Sara stores her potatoes together with beets, the potatoes will not sprout.
(D) If a carrot patch is covered with mulch in the fall. the carrots can be left in the ground until spring Without a mulch cover, carrots stored in the ground can suffer frost damage. Thus, since Kevin covers his carrot patch with mulch in the fall, the carrots can safely be left in the ground.
(E) If tomatoes are not stored in a dark place, their seeds sometimes sprout. Sprouted seeds can make tomatoes inedible. Therefore, since Maria does not store her tomatoes in a dark place some of Maria s tomatoes could be inedible.
Questions 22-23
Antinuclear activist: The closing of the nuclear power plant is a victory for the antinuclear cause. It also represents a belated acknowledgment by the power industry that they cannot operate such plants safely.
Nuclear power plant manager : It represents no such thing. The availability of cheap power from nonnuclear sources. together with the cost of mandated safety inspections and safety repairs, made continued operation uneconomic. Thus it was not safety considerations but economic considerations taht dictated the plant s closing.
上一页 [1] [2] [3] [4] [5] [6] 下一页
责任编辑：wangpeng6151
