[face=Georgia]14. Cafieine can kill or inhibit（抑制） the growth of the larvae of several species of insects. One recent experiment showed that tobacco hornworm larvae die when they ingest a preparation that consists in part of finely powdered tea leaves which contain caffeine. This result is evidence for the hypothesis that the presence of non-negligible quantities of caffeine in various parts of many diverse species of plants is not accidental but evolved as a defense for those plants.
The argument assumes that
(A) caffeine-producing plants are an important raw material in the many facture of commercial insecticides
(B) caffeine is stored in leaves and other parts of caffeine-producing plants in concentrations roughly equal to the caffeine concentration of the preparation fed to the tobacco hornworm larvae
(C) caffeine-producing plants grow wherever insect larvae pose a major threat to indigenous plants or once posed a major threat to the ancestors of those plants
(D) the tobacco plant is among the plant species that produce caffeine for their own defense
(E) caffeine-producing plants or their ancestors have at some time been subject to being led upon by creatures sensitive to caffeine
这个题目的答案是E但是E答案是十分不清楚的。可以问问。E是什么意思？
17. A new silencing device for domestic appliances operates by producing sound waves that cancel out（低偿） the sound waves produced by the appliance. The device unlike conventional silencers actively eliminates the noise the appliance makes and for that reason vacuum cleaners designed to incorporate the new device will operate with much lower electricity consumption than conventional vacuum cleaners.
Which one of the following if true most helps to explain why the new silencing device will make lower electricity consumption possible
(A) Designers of vacuum cleaner motors typically nave to compromise the motors' efficiency in order to reduce noise production
(B) The device runs on electricity drawn from the appliance's main power supply
(C) Conventional vacuum cleaners often use spinning brushes to loosen dirt in addition to using suction to remove dirt
(D) Governmental standards for such domestic appliances as vacuum cleaners allow higher electricity consumption when vacuum cleaners are quieter
(E) The need to incorporate silencers in conventional vacuum cleaners makes them heavier and less mobile than they might otherwise be
这个题目的A答案好像是不完整的。谓语是什么？又是如何解释的？
18. Because dinosaurs were reptiles, scientists once assumed that, like all reptiles alive today, dinosaurs were cold-blooded. The recent discovery of dinosaur fossils in the northern arctic however has led a number of researchers to conclude that at least some dinosaurs might have been warm-blooded. These researchers point out that only warm-blooded animals could have withstood the frigid temperatures that are characteristic of arctic winters, whereas cold-blooded animals would have frozen to death in the extreme cold.
Which one of the following if true weakens the researchers' argument?
(A) Today's reptiles are generally confined to regions of temperate or even tropical climates
(B) The fossils show the arctic dinosaurs to have been substantially smaller than other known species of dinosaurs.
(C) The arctic dinosaur fossils were found alongside fossils of plants known for their ability to withstand extremely cold temperatures.
(D) The number of fossils found together indicates herds of dinosaurs so large that they would need to migrate to find a continual food supply
(E) Experts on prehistoric climatic conditions believe that winter temperatures in the prehistoric northern arctic were not significantly different from what they are today.
这个题目答案选D真是不知道是怎么削弱原文 的。
23. Reporting on a civil war a journalist encountered evidence that refugees were starving because the government would not permit food shipments to a rebel-held area. Government censors deleted all mention of the government's role in the starvation from the journalist's report which had not implicated either nature or the rebels in the starvation. The journalist concluded that it was ethically permissible to file the censored report because the journalist's news agency would precede it with the notice "Cleared by government censors."
Which one of the following ethical criteria if valid would serve to support the journalist's conclusion while placing the least constraint on the flow of reported information?
(A) It is ethical in general to report known facts but unethical to do so while omitting other known facts if the omitted facts would substantially alter an impression of a person or institution that would be congruent with the reported facts.
(B) In a situation of conflict, it is ethical to report known facts and unethical to fail to report known facts that would tend to exonerate party to the conflict
(C) In a situation of censorship, it is unethical make any report if the government represented by the censor deletes from the report material unfavorable to that government
(D) It is ethical in general to report known facts but unethical to make a report in a situation of censorship if relevant facts have been deleted by the censor unless the recipient of the report is warned that censorship existed
(E) Although it is ethical in general to report known facts it is unethical to make a report from which a censor has deleted relevant facts unless the recipient of the report is warned that there was censorship and the reported facts do not by themselves give a misleading impression.
1. I think there is a typo in E. "led upon" should be "fed upon". And the meaning is more clearer. The experient used tea leaves on tobacco worms. So it has to been true that those caffeine-producing plants have to have some "enemies" that can be fended off by caffeine. Otherwise, self-defense does not make sense.
2. Another typo. "nave" should be "have". A points out that conventional vaccums traded electricity efficiency for lower noise. Now noise can be controlled, efficiency can be resotred.
3. D indicates that these D did not live in arctic area. They simply moved around for food and died there. C is misleading. But shelter does not help cold-blood animal as their body temp is the same as the environment. In another word, the shelter will not make their blood "warm".
京公网安备11010202008513号 京ICP证101109号 京ICP备12012021号
发表于 2003-7-17 11:53:00
