单选题 While it can't yet be said that every mouthful of food has been changed through genetic engineering, it is likely that almost every American has had a mouthful of engineered food.
Take the soybean, for example. About 55 percent of last year's crop was genetically engineered in some fashion, reports the American Soybean Association. And though few Americans sit down to a plate of soybeans for dinner, these soybeans arrive through the back door as an additive to scores of foods like cooking oils, salad dressings, coffee creamers, beer, cereals and candy.
America is on the verge of a second green revolution. The first tripled world food output over the course of a mere three decades during the late 20th century. Scientists boosted crop yields by crossbreeding (杂交) related plants that add desirable traits. Then farmers added fertilizer, pesticide, and irrigation in order to make the high-yield crops thrive.
Now that those gains are leveling off, scientists are looking to biotechnology to increase food production even more. This time, instead of breeding plants with their closest relatives, scientists are inserting genes. For example, genes from flounders can help ordinary plants like tomatoes and strawberries fight the cold. Researchers are also inserting bacterial genes into corn and soybean plants to better protect them from insects or render them immune to certain herbicides
The technology has enormous potential. The application of biotechnology is going to produce a set of possibilities that we simply cannot conceive of, even in our most imaginative flights of fancy. For farmers, crops engineered with genes that resist cold, drought, or other adverse weather conditions can boost crop yields with less money and effort. For consumers, that could mean cheaper food. Such crops would also help feed and better nourish people in developing nations, such as drought-ridden Africa.
But as these crops begin infiltrating (渗透) our food supply, environmental and consumer groups have begun to question whether potential risks to the environment and human health have been adequately studied. Last year, for example, biologists for the first time found evidence suggesting that planting genetically modified corn in open fields may kill butterflies who feed on the corn's pollen. Scientists are also questioning whether foods with a gene inserted to improve one area of their performance could prove detrimental in another: For one thing, the genes might cause allergic reactions in people who never had a reaction to that food before.

单选题 The example of the soybean the author takes is to prove that ______.
A. Americans are fond of soybeans
B. every mouthful of soybean has been changed by genetic engineering
C. America is on the verge of a second green revolution
D. soybean is treated as an additive to scores of foods

单选题 What is the main purpose of the first green revolution in America?
A. To crossbreed the related plants.
B. To add the desirable traits to the plants.
C. To realize the green revolution in three decades.
D. To make the high-yield crops thrive.

单选题 What's the biggest difference between the first and second green revolution in America?
A. The first green revolution is to improve the food output while the second is not.
B. The second green revolution is based on the theory of inserting genes while the first depends on that of crossbreeding.
C. The technology that is used in the second green revolution has much more enormous potential than that of the first's.
D. The second green revolution has caused harm to the environment while the first has not.

单选题 What's the main idea of the last paragraph?
A. Crops begin infiltrating our food supply.
B. The application of biotechnology will cause social questions as well as bring benefits to human beings.
C. The application of biotechnology is also questioned by some other people.
D. The application of biotechnology will bring enormous business to America.

单选题 The best title for this passage might be ______.
A. Biotechnology—Another Green Revolution
B. Biotechnology—Hope and Concerns
C. Soybean—the Future Dinner Food for Americans
D. Scientific Research in Agriculture