Many Americans harbour a grossly distorted and exaggerated view of most of the risks surrounding food. Fergus Clydesdale, head of the department of food science and nutrition at the University of Massachusetts-Amherst, says bluntly that if the dangers from bacterially contaminated chicken were as great as some people believe. “the streets would be littered with people lying here and there. ”
　　Though the public increasingly demands no-risk food, there is no such thing. Bruce Ames, chairman of the biochemistry department at the University of California , Berkeley, points out that up to 10% of a plant's weight is made up of natural pesticides (杀虫剂). Says he :“Since plants do not have jaws or teeth to protect themselves, they employ chemical warfare. ” And many naturally produced chemicals, though occurring in tiny amounts, prove in laboratory tests to be strong carcinogens-a substance which can cause cancer. Mushrooms (磨菇) might be banned if they were judged by the same standards that apply to food additives(添加剂). Declares Christina Stark, a nutritionist at Cornell University :“We've got fat worse natural chemicals in the food supply than anything man-made. ”
　　Yet the issues are not that simple. While Americans have no reason to be terrified to sit down at the dinner table, they have every reason to demand significant improvements in food and water safety. They unconsciously and unwillingly take in too much of too many dangerous chemicals. If food already contains natural carcinogens, it does not make much sense to add dozens of new man-made ones. Though most people will withstand the small amounts of contaminants generally found in food and water, at least a few individuals will probably get cancer one day be cause of what they eat and drink.
　　To make good food and water supplies even better, the Government needs to tighten its regulatory standards, stiffen its inspection program and strengthen its enforcement policies. The food industry should modify some long-accepted practices or turn to less hazardous alternatives. Perhaps most important, consumers will have to do a better job of learning how to handle and cook food properly. The problems that need to be tackled exist all along the food-supply chain, from field s to processing plants to kitchens.

　　21.What does the author think of the Americans' view of their food?
　　A) They overstate the government's interference with the food industry.
　　B) They are overoptimistic about the safety of their food.
　　C) They overestimate the hazards of their food.
　　D) They overlook the risks of the food they eat.

　　22.The author considers it impossible to obtain no-risk food because .
　　A) no food is free from pollution in the environment.
　　B) pesticides are widely used in agriculture.
　　C) many vegetables contain dangerous natural chemicals.
　　D) almost all foods have additives.

　　23.By saying“they employ chemical warfare”(Line 4, Para. 2), Bruce Ames means “_______".
　　A) plants produce certain chemicals to combat pests and diseases.
　　B) plants absorb useful chemicals to promote their growth.
　　C) farmers use man-made chemicals to dissolve the natural chemicals in plants.
　　D) farmers use chemicals to protect plants against pests and diseases.

　　24.The reduction of the possible hazards in food ultimately depends on .
　　A) the government. B) the consumer.
　　C) the processor. D) the grower.

　　25.What is the message the author wants to 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.

　　答案：21.C   22.C   23.A   24.B   25.D