求大牛解答４道ＣＲ题，THX！！！

RachelXu

1.Electronic computer chips made of tiny silicon wafers now regularly contain millions of electronic switches.Unfortunately, electronic switches that are this small cannot withstand intense radiation.Micro-Mechanics plans to produce a chip that, because it uses only microscopic mechanical switches, will be invulnerable to radiation damage.The switches will, however, be slower than electronic switches and the chip will contain only 12,000 switches.

For there to be a market for Micro-Mechanics's chip as a result of the apparent advantage described above, each of the following would have to be true EXCEPT:

A. There will be applications in which the speed attainable by an electronic switch is not essential.

B. Switches used on electronic chips that contain only 12,000 switches are more vulnerable to radiation damage than the switches on Micro-Mechanics's chip will be.

C. There will be applications for computer chips in environments where the chips may have to survive intense radiation.

D. Some devices in which computer chips will be used will have other components that will be able to function during or after exposure to radiation.

E. Manufacturers are able to protect electronic computer chips against exposure to intense radiation, where this protection is necessary.

答案是E ，我选对了，但对D还是有点小纠结，有没有好心人能把我的结解开。。。谢谢

2.Twenty years ago, Balzania put in place regulations requiring operators of surface mines to pay for the reclamation of mined-out land.Since then, reclamation technology has not improved.Yet, the average reclamation cost for a surface coal mine being reclaimed today is only four dollars per ton of coal that the mine produced, less than half what it cost to reclaim surface mines in the years immediately after the regulations took effect.

Which of the following, if true, most helps to account for the drop in reclamation costs described?

A. Even after Balzania began requiring surface mine operators to pay reclamation costs, coal mines in Balzania continued to be less expensive to operate than coal mines in almost any other country.

B. In the twenty years since the regulations took effect, the use of coal as a fuel has declined from the level it was at in the previous twenty years.

C. Mine operators have generally ceased surface mining in the mountainous areas of Balzania because reclamation costs per ton of coal produced are particularly high for mines in such areas.

D. Even after Balzania began requiring surface mine operators to pay reclamation costs, surface mines continued to produce coal at a lower total cost than underground mines.

E. As compared to twenty years ago, a greater percentage of the coal mined in Balzania today comes from surface mines.

答案是C，真心不懂。。。我选了B

3.
Which of the following most logically completes the argument?

When people engage in activities that help others, their brain releases endorphins, the brain’s natural opiates, which induce in people a feeling of well-being.It has been suggested that regular release of endorphins increases people’s longevity, and a statistic on adults who regularly engage in volunteer work helping others shows that they live longer, on average, than adults who do not volunteer.However, that statistic would be what we would expect even if volunteering does not boost longevity, because __________.

A. in the communities studied, women were much more likely to do regular volunteer work than men were, and women tend to live longer than men do

B. the number of young adults who do regular volunteer work is on the increase

C. the feelings of well-being induced by endorphins can, at least for a time, mask the symptoms of various conditions and diseases, provided the symptoms are mild

D. it is rare for a person to keep up a regular schedule of volunteer work throughout his or her life

E. some people find that keeping a commitment to do regular volunteer work becomes a source of stress in their lives

答案选A，我选了C。开始就把A给干掉了。。。

4
Excavations of the Roman city of Sepphorishave uncovered numerous detailed mosaics depicting several readily identifiable animal species:a hare, a partridge, and various Mediterranean fish.Oddly, most of the species represented did not live in the Sepphoris region when these mosaics were created.Since identical motifs appear in mosaics found in other Roman cities, however, the mosaics of Sepphoris were very likely created by traveling artisans from some other part of the Roman Empire
.


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

A. The Sepphoris mosaics are not composed exclusively of types of stones found naturally in the Sepphoris area.

B. There is no single region to which all the species depicted in the Sepphoris mosaics are native.

C. No motifs appear in the Sepphoris mosaics that do not also appear in the mosaics of some other Roman city.

D. All of the animal figures in the Sepphoris mosaics are readily identifiable as representations of known species.

E. There was not a common repertory of mosaic designs with which artisans who lived in various parts of the Roman Empirewere familiar.



选E，我对了，但是不太确定怎么做的。

RachelXu

没有人回答吗。。。我自己顶一下~