请教prep几道题：）

prep1 24.       (29155-!-item-!-188;#058&003857)

Tiger beetles are such fast runners that they can capture virtually any nonflying insect.  However, when running toward an insect, the beetles intermittently stop, and then, a moment later, resume their attack.  Perhaps they cannot maintain their pace and must pause for a moment's rest; but an alternative hypothesis is that while running tiger beetles are unable to process the resulting rapidly changing visual information, and so quickly go blind and stop.

Which of the following, if discovered in experiments using artificially moved prey insects, would support one of the two hypotheses and undermine the other?

(A) When a prey insect is moved directly toward a beetle that has been chasing it, the beetle immediately turns and runs away without its usual intermittent stopping.

 (B) In pursuing a moving insect, the beetles usually respond immediately to changes in the insect's direction, and pause equally frequently whether the chase is up or down an incline.

(C) The beetles maintain a fixed time interval between pauses, although when an insect that had been stationary begins to flee, the beetle increases its speed after its next pause.

(D) If, when a beetle pauses, it has not gained on the insect it is pursuing, the beetle generally ends its pursuit.

(E) When an obstacle is suddenly introduced just in front of running beetles, the beetles sometimes stop immediately, but they never respond by running around the barrier.

虽然我现在也能理解c勒，但我想知道这种题是要否定一个然后肯定一个吗？希望有人能帮我在顺顺这个题目。。。还是不太清楚

prep1 50.    (34317-!-item-!-188;#058&007562)

Generally scientists enter their field with the goal of doing important new research and accept as their colleagues those with similar motivation.  Therefore, when any scientist wins renown as an expounder of science to general audiences, most other scientists conclude that this popularizer should no longer be regarded as a true colleague.

The explanation offered above for the low esteem in which scientific popularizers are held by research scientists assumes that

(A) serious scientific research is not a solitary activity, but relies on active cooperation among a group of colleagues

(B) research scientists tend not to regard as colleagues those scientists whose renown they envy

(C) a scientist can become a famous popularizer without having completed any important research

(D) research scientists believe that those who are well known as popularizers of science are not motivated to do important new research

(E) no important new research can be accessible to or accurately assessed by those who are not themselves scientists

答案选d，不是很理解。为什么low esteem的人就会这么想啊。。。

prep2 8.  (24449-!-item-!-188;#058&001338)

Which of the following most logically completes the argument?

Utrania was formerly a major petroleum exporter, but in recent decades economic stagnation and restrictive regulations inhibited investment in new oil fields.  In consequence, Utranian oil exports dropped steadily as old fields became depleted.  Utrania's currently improving economic situation, together with less-restrictive regulations, will undoubtedly result in the rapid development of new fields.  However, it would be premature to conclude that the rapid development of new fields will result in higher oil exports, because __________.

 (A) the price of oil is expected to remain relatively stable over the next several years

(B) the improvement in the economic situation in Utrania is expected to result in a dramatic increase in the proportion of Utranians who own automobiles

(C) most of the investment in new oil fields in Utrania is expected to come from foreign sources

(D) new technology is available to recover oil from old oil fields formerly regarded as depleted

(E) many of the new oil fields in Utrania are likely to be as productive as those that were developed during the period when Utrania was a major oil exporter

我觉得e也可以啊，为什么b就对？