托福考试易错题（2019/2/22）

Cancer andChemicals
Last year,California governor GeorgeDeukmejian called together many of the state’s best scientific minds to begin implementing Proposition 65, the state’s SafeDrinking Water and ToxicEnforcementAct. This new law bans industries from discharging chemical suspected of causing cancer (carcinogens) or birth defects into water supplies. Some claim it will also require warning labels on everything that might cause cancer.
A、day of esoteric science and incomprehensible jargon was predicteD、ButBruceAmes,Chairman of theDepartment ofBiochemistry at the University ofCalifornia atBerkeley, had plans to liven the proceedings. Walking into the room,Ames looked like the quintessential scientist: wire-rimmed bifocals, rumpled suit, tousled hair and a sallow complexion that showed he spent more time in his laboratory than in theCalifornia sunshine.As someone intoned about the mechanisms of carcinogenesis,Ames began to interject his own views. "The whole world is chock—full of carcinogens,"Ames declareD、"A、beer, with its 700 parts per billion of formaldehyde and five parts per 100 of alcohol is a thousand times more hazardous than anything in the water. If you have beer on your breath, does that mean you have to warn everyone who comes within ten feet of you " In an era when headlines shout about the latest cancer scare,Ames has a different message: the levels of most man-made carcinogens are generally so low that any danger is trivial compared with the levels of natural carcinogens.
Ames is not a quack.At age 59, he is one of the nation’s most respected authorities on carcinogenesis.
ButAmes slaughters sacred cows. He’s taking on the environmental movement, which some have called the single most important social movement of the 20th century.Based on animal tests of nearly 1000 chemicals, the data show that daily consumption of the average peanut-butter sandwich, which contains traces of aflatoxin (a naturally occurring mold carcinogen in peanuts), is 100 times more dangerous than our daily intake ofDDT from food, and that a glass of the most polluted well water in the Silicon Valley is 1000 times less of cancer risk than a glass of wine or beer is. He’s not advising people to stop consuming peanut-butter, beer and wine. What he’s saying is that most cancer risks created by man are trivial compared with everyday natural risks, and it’s not clear how many of these are real risks.Both types distract attention from such enormous risk factors as tobacco.
A、[■]Ames’s cancer research began about 25 years ago over a bag of potato chips.
B、[■] It struck him that no one knew what each chemical did to human genes, and there was no easy way to find out.
C、[■]At that time, scientists testing for carcinogenicity had to set up time-consuming and costly lab experiments on rats and mice.
D、[■]Armed with the knowledge that bacteria are sensitive to substances that cause mutation, and that carcinogens were likely to be mutagens,Ames developed a carcinogen test using bacteriA、TheAmes test was hailed as a major scientific development and is now used worldwide.
One day in 1974,Ames, now teaching atBerkeley, suggested that some students test various household products. To his surprise, many common hair dyes tested positive, as did a flame retardant used in children’s pajamas.Almost overnight,Ames became a hero of environmentalists when his findings led to new regulations and bans on certain chemicals. For the next decade public concern over carcinogens continued to rise. In fact, about half of all chemicals tested byAmes—both natural and man-made—turned out to be potentially carcinogenic when given in enormous dose to rats and mice.Ames at first assumed he had erred with his test. He hadn’t. His error had been making the common, but naive, assumption that only man-made chemicals coul

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