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U.S. Life Expectancy Hits New HighLife expectancy rates in the United States are at an all-time high, with people born in 2005 projected to live for nearly 78 years, a new federal study finds.The finding reflects a continuing trend of increasing life expectancy that began in 1955, when the average American lived to be 69.6 years old. By 1995, life expectancy was 75.8 years, and by 2005, it had risen to 77.9 years, according to the report released Wednesday."This is good news", said report coauthor Donna Hoyert, a health scientist at the National Center for Health Statistics. "It"s even beer news that it is a continuation of trends, so it is a long period of continuing improvement."Despite the upward trend, the United States still has a lower life expectancy than some 40 other countries, according to the U. S. Census (人口普查) Bureau. The country with the longest life expectancy is Andorra at 83.5 years, followed by Japan, Macau, San Marino and Singapore.Much of the increase owes to declining death rates from the three leading causes of death in the country-heart disease, cancer and stroke.In addition, in 2005, the U. S. death rate dropped to an all-time low of less than 800 deaths per 100,000.Dr. David Katz director of the Prevention Research Center at Yale University School of Medicine, said, "News that life expectancy is increasing is, of course, good. But the evidence we have suggests that there is more chronic disease than ever in the U. S."Adding years to life is a good thing, Katz said. "But adding vital life to years is at least equally important. If we care about living well, and not just longer, we still have our work cut out for us." he said. Since 1955, life expectancy rates in the U. S. have ______.

A. moved up and down
B. been declining
C. been on the rise
D. remained steady

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Diseases of Agricultural PlantsPlants, like animals, are subject to diseases of various kinds. It has been estimated that some 30,000 different diseases attack our economic plants; forty are known to attack corn, and about as many attack wheat. The results of unchecked plant disease are all too obvious in countries which have marginal food supplies. The problem will soon be more widespread as the population of the world increases at its frightening rate. Even in countries which are now amply fed by their agricultural products there could soon be critical food shortages. It is easy to imagine the consequences of some disastrous attack on one of the major crops; the resulting famines could kill millions of people, and the resulting hardship on other millions could cause political upheavals disastrous to the order of the world.Some plants have relative immunity to a great many diseases, while others have a susceptibility to them. The tolerance of a particular plant changes as the growing conditions change. A blight may be but a local infection easily controlled; on the other hand it can attack particular plants in a whole region or nation. An example is the blight which killed virtually every chestnut tree in North America. Another is the famous potato blight in Ireland in the last century. As a result of that, it was estimated that one million people died of starvation and related ailments.Plant pathologists have made remarkable strides in identifying the pathogens of the various diseases. Bacteria may invade a plant through an infestation of insect parasites carrying the pathogen. A plant can also be inoculated by man. Other diseases might be caused by fungus which attacks the plant in the form of a mold or smut or rust. Frequently such a primary infection will weaken the plant so that a secondary infection may result from its lack of tolerance. The symptoms shown may cause an error in diagnosis, so that treatment may be directed toward bacteria which could be the result of a susceptibility caused by a primary virus infection. According to this passage, which of the following would a plant disease result in if left unchecked

A world war.
Border conflicts.
C. Rations of grain and meat.
D. Social upheavals.

Smoking Can Increase Depressive Symptoms in TeensWhile some teenagers may puff on cigarettes to "self-medicate" (自我治疗) against the blues (忧郁), scientists at the University of Toronto and the University of Montreal have found that smoking may actually 1 depressive symptoms in some teens."This observational study is one of the few to examine the perceived 2 benefits of smoking among teens," says lead researcher Michael Chariton, a research associate at the Ontario Tobacco Research Unit of the University of Toronto. " 3 cigarettes may appear to have self-medicating effects or to improve mood, in the long 4 we found that teens who started to smoke reported higher depressive symptoms. "As part of the study, some 662 high school teenagers completed up to 20 questionnaires about their use of cigarettes to 5 mood. Secondary schools were selected to provide a mix of French and English participants, urban and rural schools, and schools 6 in high, moderate and low socioeconomic neighborhoods.Participants were divided into three 7 : never smokers; smokers who did not use cigarettes to self-medicate improve mood or physical 8 ; smokers who used cigarettes to self-medicate. Depressive symptoms were measured using a scale that asked how often participants felt too tired to do things; had 9 going to sleep or staying asleep; felt unhappy, sad, or depressed; felt hopeless about the future; felt anxious or tense; and worried too much about things."Smokers who used cigarettes as mood 10 had higher risks of elevated (提升) depressive symptoms 11 teens who had never smoked," says co-researcher Jennifer O"Loughlin, a professor at the University of Montreal Department of Social and Preventive Medicine. "Our study found that teen smokers who reported emotional benefits from smoking are 12 higher risk of depressive symptoms."The 13 between depression and smoking exits 14 among that use cigarettes to feel better. " It"s 15 to emphasize that depressive symptom scores were higher among teenagers who reported emotional benefits from smoking after they began to smoke," says Dr. Chariton.

A. road
B. term
C. journey
D. distance

I don"t think Peter is too young to take care of the pet dog properly.

A. correctly
B. accordingly
C. exactly
D. actively

Diseases of Agricultural PlantsPlants, like animals, are subject to diseases of various kinds. It has been estimated that some 30,000 different diseases attack our economic plants; forty are known to attack corn, and about as many attack wheat. The results of unchecked plant disease are all too obvious in countries which have marginal food supplies. The problem will soon be more widespread as the population of the world increases at its frightening rate. Even in countries which are now amply fed by their agricultural products there could soon be critical food shortages. It is easy to imagine the consequences of some disastrous attack on one of the major crops; the resulting famines could kill millions of people, and the resulting hardship on other millions could cause political upheavals disastrous to the order of the world.Some plants have relative immunity to a great many diseases, while others have a susceptibility to them. The tolerance of a particular plant changes as the growing conditions change. A blight may be but a local infection easily controlled; on the other hand it can attack particular plants in a whole region or nation. An example is the blight which killed virtually every chestnut tree in North America. Another is the famous potato blight in Ireland in the last century. As a result of that, it was estimated that one million people died of starvation and related ailments.Plant pathologists have made remarkable strides in identifying the pathogens of the various diseases. Bacteria may invade a plant through an infestation of insect parasites carrying the pathogen. A plant can also be inoculated by man. Other diseases might be caused by fungus which attacks the plant in the form of a mold or smut or rust. Frequently such a primary infection will weaken the plant so that a secondary infection may result from its lack of tolerance. The symptoms shown may cause an error in diagnosis, so that treatment may be directed toward bacteria which could be the result of a susceptibility caused by a primary virus infection. What is the main idea of the second paragraph

A. Some plants have relative immunity to a great many diseases, while others have a susceptibility to them.
B. The tolerance of a particular plant changes as the growing conditions change.
C. A blight killed virtually every chestnut tree in North America.
D. A blight may be a national infection.

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