单项选择题 Soap for the ages You really can take a can of soup with you to the bomb shelter, and if it's not dented or damaged, it will last for years. But it may not taste quite right. Over time, says Michael Doyle, a food microbiologist at the University of Georgia's Center for Food Safety and Quality Enhancement, the interaction between the acid in the soup and the lining of the steel can may produce sulfur dioxide gas, causing the can to swell. The pressure and high temperature used in the canning process mean that the soup will remain safe as long as no pathogen makes its way into a damaged can, says Rhona Applebaum of the National Food Processors Association. The soup won' t make you sick, but levels of certain nutrients will decrease. The color of the food may change, as well as its tartness or tanginess. Vegetables may lose their crispness. And the food might develop a sulfurous taste .because of the production of hydrogen sulfide; if it contains meat, it might smell or taste slightly of ammonia. Best bet: If the can is swollen, toss it.What Cause's the soup can to swell?A．Meat.B．Sulfur dioxide gas.C．Hydrogen sulfide.D．Pathogen.

未知题型 建设社会主义法治体系要把( )的原则贯穿立法全过程，完善立法体制机制，坚持立改废释并举。

单项选择题 What is the future for cities? Why does one inner-city neighborhood become a slum and another a high-class district? Why does one city attract new shoppers and visitors while another languishes? Camden, New Jersey, displays the strong contrasts that characterize American urban areas. The central city of Camden houses an isolated underclass, while suburban Camden County prospers. The population of the city of Camden has declined from 117,000 in 1960 to less than80,000 today. Nearly 85 percent of the city's residents are black and Hispanic, while the white population has declined from 90,000 in 1960 to 10,000 today. Only 1 percent of the households remaining have annual incomes of more than $ 50,000, compared with 20 percent in the rest of the country and 10 percent among all black h6useholds. More than 40 percent of Camden's residents are under eighteen, closer to the level found in developing countries than to the rest of the United States. Job prospects are not promising for these young people, because more than half have left school without obtaining a high-school diploma. In the past, Camden's youths could find jobs in factories that produced Campbell's soups, Esterbrook pens, and RCA Victor records, radios, and televisions, but the city has lost 90 percent of its industrial jobs. The Esterbrook and Campbell factories in Camden are closed, though Campbell's corporate offices remain; General Electric now operates the former RCA factory but with a labor force at only 15 percent of the level during the 1960s. Camden' s unemployment rate is more than twice the national average. As Camden's population and industries decline, few shops have enough customers to remain open. The city once had thirteen movie theaters, but none are left. The murder rate soared after gangs carved up the city into districts during the mid-1980s to control cocaine trafficking. Meanwhile, Camden County -- excluding the city -- has grown from 275,000 in 1960 to more than 400,000 today. Cherry Hill has more than 75,000 residents today, compared to less than 10,000 in 1960, and will surpass Camden as the largest city in the county before the end of the decade. About 85 percent of Cherry Hill's high-school graduates go on to college. Cherry Hill has attracted so many new jobs that the major obstacle to further economic growth is a shortage of qualified workers. Camden' s mismatch between the locations of people, jobs, resources, and services exemplifies the urban crisis throughout the United States, as well as in other countries. Geographers help us to understand why these patterns arise, and what can be done about them.Which of the following is NOT true?A．Camden County is larger than the city of Camden.B．Cherry Hill's economy is sluggish.C．The white people have moved to the suburbs.D．General Electric now employs less workers than it used to.