很难的prep逻辑题......请教啊。

1.An unusually severe winter occurred in Europe after the continent was blanketed by a blue haze resulting from the eruption of the Laki Volcano in the European republic of Iceland in the summer of 1984.  Thus, it is evident that major eruptions cause the atmosphere to become cooler than it would be otherwise.

Which of the following statements, if true, most seriously weakens the argument above?

(A) The cooling effect triggered by volcanic eruptions in 1985 was counteracted by an unusual warming of Pacific waters.
(B) There is a strong statistical link between volcanic eruptions and the severity of the rainy season in India.
(C) A few months after El Chichn's large eruption in April 1982, air temperatures throughout the region remained higher than expected, given the long-term weather trends.
(D) The climatic effects of major volcanic eruptions can temporarily mask the general warming trend resulting from an excess of carbon dioxide in the atmosphere.
(E) Three months after an early springtime eruption in South America during the late 19th century, sea surface temperatures near the coast began to fall.
答案选C。可是文章的结论有一个major，也就是说存在有个例的确会 hot the weather。那么C选项就是这样的个例了？？

2.Some airlines allegedly reduce fares on certain routes to a level at which they lose money, in order to drive competitors off those routes.  However, this method of eliminating competition cannot be profitable in the long run.  Once an airline successfully implements this method, any attempt to recoup the earlier losses by charging high fares on that route for an extended period would only provide competitors with a better opportunity to undercut the airline's fares.

Which of the following, if true, most seriously weakens the argument?

(A) In some countries it is not illegal for a company to drive away competitors by selling a product below cost.
(B) Airline executives generally believe that a company that once underpriced its fares to drive away competitors is very likely to do so again if new competitors emerge.
(C) As part of promotions designed to attract new customers, airlines sometimes reduce their ticket prices to below an economically sustainable level.
(D) On deciding to stop serving particular routes, most airlines shift resources to other routes rather than reduce the size of their operations.
(E) When airlines dramatically reduce their fares on a particular route, the total number of air passengers on that route increases greatly.

题干最后一句话如何理解呢？

3.With a record number of new companies starting up in Derderia and with previously established companies adding many jobs, a record number of new jobs were created last year in the Derderian economy.  This year, previously established companies will not be adding as many new jobs overall as such companies added last year.  Therefore, unless a record number of companies start up this year, Derderia will not break its record for new jobs created.

Which of the following is an assumption on which the argument relies?

(A) Each year, new companies starting up create more new jobs overall than do previously established companies.
(B) Companies established last year will not add a greater number of jobs overall this year than they did last year.
(C) This year, the new companies starting up will not provide substantially more jobs per company than did new companies last year.
(D) This year, the overall number of jobs created by previously established companies will be less than the overall number of jobs lost at those companies.
(E) The number of jobs created in the Derderian economy last year was substantially larger than the number of jobs lost last year.
如何理解此题的逻辑呢？

4.Film Director:  It is true that certain characters and plot twists in my newly released film The Big Heist are strikingly similar to characters and plot twists in Thieves, a movie that came out last year.  Based on these similarities, the film studio that produced Thieves is now accusing me of taking ideas from that film.  The accusation is clearly without merit.  All production work on The Big Heist was actually completed months before Thieves was released.

Which of the following, if true, provides the strongest support for the director's rejection of the accusation?

(A) Before Thieves began production, its script had been circulating for several years among various film studios, including the studio that produced The Big Heist.
(B) The characters and plot twists that are most similar in the two films have close parallels in many earlier films of the same genre.
(C) The film studio that produced Thieves seldom produces films in this genre.
纠结于B和C两个选项啊。

不明白呀。