1、n dangerous natural chemicalsD) almost all foods have additives（C）23.By saying “they employ chemical warfare” (Line 4, Para. 2), Bruce Ames means “_”.A) plants produce certain chemicals to combat pests and diseasesB) plants absorb useful chemicals to promote their growthC) farmers use man-made chemi
2、cals to dissolve the natural chemicals in plantsD) farmers use chemicals to protect plants against pests and diseases（A）24.The reduction of the possible hazards in food ultimately depends on _.A) the governmentB) the consumerC) the processorD) the grower（B）25.What is the message the author wants to
3、convey in the passage?A) Eating and drinking have become more hazardous than before.B) Immediate measures must be taken to improve food production and processing.C) Health food is not a dream in modern society.D) There is reason for caution but no cause for alarm with regard to food consumption.（D）Q
4、uestions 26 to 30 are based on the following passage.There are some each phenomena you can count on, but the magnetic field, someday is not of them. It fluctuates in strength, drifts from its axis, and every few 100,000 years undergo, dramatic polarity reversal-a period when North Pole becomes South
5、 Pole and South Pole becomes North Pole. But how is the field generated, and why is it so unstable?Groundbreaking research by two French geophysicists promises to shed some light on the mystery. Using 80 metres of deep sea sediment (沉淀物) core, they have obtained measurements lots of magnetic-field i
6、ntensity that span 11 polarity reversals and four million years. The analysis reveals that intensity appears to fluctuate with a clear, well-defined rhythm. Although the strength of the magnetic field varies irregularly during the short term, there seems to be an inevitable long-term decline precedi
7、ng each polarity reversal. When the poles flipa process that takes several hundred thousand years-the magnetic field rapidly regains its strength and the cycle is repeated.The results have caused a stir among geophysicists. The magnetic field is thought to originate from molten (熔化的) iron in the out
8、er core, 3,000 kilometers beneath the earths surface. By studying mineral grains found in material ranging from rocks to clay articles, previous researchers have already been able to identify reversals dating back 170 million years, including the most recent switch 730,000 years ago. How and why the
9、y occur, however, has been widely debated. Several theories link polarity flips to external disasters such as meteor (陨星) impacts. But Peter Olson, a geophysicist at the Johns Hopkins University in Baltimore, says this is unlikely if the French researchers are right. In fact, Olson says intensity th
10、at predictably declines from one reversal to the next contradicts 90 percent of the models currently under study. If the results prove to be valid geophysicists will have a new theory to guide them in their quest to understand the earths inner physics. It certainly points the direction for future re
11、search.26.Which of the following titles is most appropriate to the passage?A) Polarity Reversal: A Fantastic Phenomenon of Nature.B) Measurement of the Earths Magnetic-Field Intensity.C) Formation of the Two Poles of the Earth.D) A New Approach to the Study or Geophysics.（D）27.The word “flip” (Line
12、6, Para. 2) most probably means “_”.A) declineB) intensifyC) fluctuateD) reverse（D）28.What have the two French geophysicists discovered in their research?A) Some regularity in the changes of the earths magnetic field.B) Some causes of the fluctuation of the earths magnetic field.C) The origin of the
13、 earths magnetic field.D) The frequency of polarity reversals.（A）29.The French geophysicists study is different from currently prevailing theories in _.A) its identification of the origin of the earths magnetic fieldB) the way the earths magnetic intensity is measuredC) its explanation of the shift
14、in the earths polarityD) the way the earths fluctuation rhythm is defined（C）30.In Peter Oslos opinion the French experiment _.A) is likely to direct further research in the inner physics of the earthB) has successfully solved the mystery of polarity reversalsC) is certain to help predict external di
15、sastersD) has caused great confusion among the worlds geophysicists（A）Questions 31 to 35 are based on the following passage.Imagine a world in which there was suddenly no emotion-a world in which human beings could feel no love or happiness, no terror or hate. Try to imagine the consequences of such
16、 a transformation. People might not be able to stay alive: knowing neither joy nor pleasure, anxiety nor fear, they would be as likely to repeat acts that hurt them as acts that were beneficial. They could not learn: they could not benefit from experience because this emotionless world would lack re
17、wards and punishments. Society would soon disappear: people would be as likely to harm one another as to provide help and support. Human relationships would not exist: in a world without friends or enemies, there could be no marriage, affection among companions, or bonds among members of groups. Soc
18、ietys economic underpinnings (支柱) would be destroyed: since earning $10 million would be no more pleasant than earning $10, there would be no incentive to work. In fact, there would be no incentives of any kind. For as we will see, incentives imply a capacity to enjoy them.In such a world, the chanc
19、es that the human species would survive are next to zero, because emotions are the basic instrument of our survival and adaptation. Emotions structure the world for us in important ways. As individuals, we categorize objects on the basis of our emotions. True we consider the length, shape, size, or
20、texture, but an objects physical aspects are less important than what it has done or can do to ushurt us, surprise us, anger us or make us joyful. We al so use categorizations colored by emotions in our families, communities, and overall society. Out of our emotional experiences with objects and events comes a social feeling of agreement that certain things and actions are good and others are bad, and we apply these categories to every aspect of our social lifefrom wh
