1.Astronomer: Observations of the Shoemaker-Levi comet onits collision course with Jupiter showed that the comet broke into fragmentsbefore entering Jupiter's atmosphere in 1994, but they did not show how bigthose fragments were. In hopes ofgaining some indication of the fragments' size, astronomers studiedspectrographic analyses of Jupiter's outer atmosphere. These analyses revealed unprecedented tracesof sulfur after the fragments' entry.Thefragments themselves almost certainly contained no sulfur, but many astronomersbelieve that the cloud layer below Jupiter's outer atmosphere does containsulfur. Since sulfur would haveseeped into the outer atmosphere if comet fragments had penetrated this cloudlayer, it is likely that some of thefragments were at least large enough to have passed through Jupiter's outeratmosphere without being burned up.
In the astronomer's argument, the two portions in boldface play which of the followingroles?
(A) The first presents a circumstance for which theastronomer offers an explanation; the second is part of that explanation.
(B) The first acknowledges a consideration that weighsagainst the conclusion of the argument; the second is that conclusion.
(C) The first acknowledges a consideration that weighsagainst the conclusion of the argument; the second provides evidence in supportof that conclusion.
(D) The first provides evidence in support of theconclusion of the argument; the second acknowledges a consideration that weighsagainst that conclusion.
(E) The first is a judgment advanced in support of theconclusion of the argument; the second is that conclusion.
思路：A：排除，因为它说第二句话是Part of that explanation;
2.Most of the world's supply of uranium currently comesfrom mines. It is possible to extracturanium from seawater, but the cost of doing so is greater than the price thaturanium fetches on the world market. Therefore, until the cost of extracting uranium from seawater cansomehow be reduced, this method of obtaining uranium is unlikely to becommercially viable.
Which of the following would it be most useful todetermine in evaluating the argument?
(A) Whether the uranium in deposits on land is rapidlybeing depleted
(B) Whether most uranium is used near where it is mined
(C) Whether there are any technological advances thatshow promise of reducing the cost of extracting uranium from seawater
(D) Whether the total amount of uranium in seawater issignificantly greater than the total amount of uranium on land
(E) Whether uranium can be extracted from freshwater at acost similar to the cost of extracting it from seawater
思路：B：是否uranium是在near where it is mined被用的，与uranium从哪开采出来的成本高低无关系，所以跟结论也无关系;
C：technological advances是无关词。有这样的技术，也不能确定这种技术会被使用，也就是说，不确定cost是否会真的会下降;有没有这样的技术和最终from seawater的cost降下来之间没有“必然”联系。 有它可以，没它也没什么!!
E：freshwater无关名词。把from freshwater和from seawater比cost是没有意义的。我们这里需要比from seawater和from land的cost;
A：是否uranium将会很快消耗光，这就预示着是否uranium on the worldmarket的价格是否会有巨大上涨，也就是uraniumcost on the world market是否会超过from seawater的uranium, 也就决定了是否this method is commerciallyviable。这是正确答案。
3. Urban air contains more sulfur dioxide than does ruralair, and plants in cities typically grow more slowly than do plants in ruralareas. In an experiment to see how muchof the difference in growth is due to sulfur dioxide, classes in an urban and arural school grew plants in greenhouses at their schools and filtered thegreenhouse air to eliminate sulfur dioxide. Plants in the urban greenhouse grew more slowly than those in the ruralgreenhouse.
Which of the following, if true, would it be mostimportant to take into account in evaluating the result?
(A) The urban school was located in a part of the city inwhich levels of sulfur dioxide in the air were usually far lower than istypical for urban areas.
(B) At both schools, the plants in the greenhouses grewmuch more quickly than did plants planted outdoors in plots near thegreenhouses.
(C) The urban class conducting the experiment was largerthan the rural class conducting the experiment.
(D) Heavy vehicular traffic such as is found in citiesconstantly deposits grime on greenhouse windows, reducing the amount of lightthat reaches the plants inside.
(E) Because of the higher levels of sulfur dioxide in theair at the urban school, the air filters for the urban school's greenhouse werechanged more frequently than were those at the rural school.
A. school located在哪不是新原因。
C: fullerenes是如何形成的，跟检测the state of earth’s crust无关;
A: 是迷惑的选项。confirming矿石含有fullerenes 需要仔细实验，说明要在矿石中发现fullerenes挺麻烦，但是并不能说明发现fullerenes会对检测fullerenes产生影响;
D: fullerenes晶体结构我们不知道，无法从它来了解the state of earth’s crust. 正确答案!
Many small roads do not have painted markings along theiredges. Clear edge markings would make iteasier for drivers to see upcoming curves and to judge the car's position onthe road, particularly when visibility is poor, and would therefore seem to bea useful contribution to road safety. However, after Greatwater County painted edge markings on all itsnarrow, winding roads, the annual accident rate along those roads actuallyincreased slightly.
Which of the following, if true, most helps to explainthe increase in accident rate?
(A) Greatwater County has an unusually high proportion ofnarrow, winding roads.
(B) In bad weather it can be nearly as difficult fordrivers to see the road as it is at night.
(C) Prior to the painting of the edge markings,Greatwater County's narrow, winding roads already had a somewhat higheraccident rate than other Greatwater County roads.
(D) Many of the accidents on narrow, winding roadsinvolve a single vehicle veering off the road, rather than the collision of twovehicles.
(E) After the markings were painted on the roads, manydrivers who had gone out of their way to avoid driving on those roads at nightno longer did so.
B: 谓语动词canbe as difficult, 没有变化;
D: 谓语动词是involve, 较难判断是否是变化的。许多事故都是涉及到单个车翻下路，而不是两车碰撞。那很有可能原来的路上的情况也是这样的。所以不能解释为什么事故率上升;
E: no longer didso表明了一种变化，并且时间也符合(after….)。以前不在这条路上开车的driver, 现在开始在这条路上开车,所以事故率有了上升。