For decades many U. S. veterans who took part in atmospheric nuclear tests have wondered whether their exposure to radiation might ultimately cost them their lives. Their private fears became a public issue in 1976 after a veteran claimed his leukemia was caused by radiation from a 1957 test series. The atomic veterans and their families, as well as researchers and policy-makers, continue to struggle for definitive answers. These have been elusive, at least in part, because a crucial piece of information has been difficult to get-the radiation dose that each individual received. In the largest study to date, researchers from the Institute of Medicine (IOM) have come up with some partial answers. But they too were limited in their ability to draw conclusions by the lack of usable information on radiation exposure. The new study focused on participants in five series of nuclear tests, all of which took place either in the Nevada desert or the South Pacific. Nearly 70, 000 soldiers, sailors, airmen, and marines were involved in at least one of these, and about 30 percent of them have now died. For comparison, researchers selected a group of 65, 000 military people serving at the same time under similar conditions, except that they did not take part in nuclear tests. After an intensive review of service and death records, researchers found no difference between the two groups in overall death rates or in total deaths from cancer. Had there been a dramatic radiation effect, it would have shown up in this comparison. The researchers also analyzed specific causes of death, including diseases linked in other studies to radiation. Here there were some differences. Among the nuclear test veterans, 14 percent more died from leukemia than those in the comparison group, although the difference lacked statistical significance and could have resulted from chance. When comparisons were made based on whether the veterans participated in nuclear tests in Nevada or in the Pacific Ocean, the differences were sharper: a 50 percent higher leukemia death rate among Nevada atomic veterans than among the comparison group. This was not true among Pacific test participants, who actually had a slightly lower, though not statistically significant leukemia death rate than those in their comparison group. 81.The passage tells us that researchers wish that they could find out______. A.when and where the veterans received the nuclear radiation B.why the amount of radiation cannot be accurately measured C.who was responsible for the veterans' deaths D.how much radiation each veteran got during the nuclear tests 82.The latest study includes a comparison made between______. A.healthy veterans and unhealthy veterans B.nuclear test participants and those with no radiation exposure C.the veterans who are still alive and those who have died D.people who died of cancer and people who took part in atomic tests 83.What can we learn about the result of the latest study? A.There was a significant difference in total deaths from cancer between the two groups. B.There was no significant difference in death rates between the two groups. C.The comparison group has a lower death rate. D.More veterans died from leukemia than from other cancers. 84.One comparison mentioned in the last paragraph was made between______. A.Pacific test participants and those who undertook the Nevada test B.Nevada atomic veterans and those who didn't take part in any nuclear tests C.Veterans in Nevada and Pacific atomic tests and the comparison group D.half of Nevada test participants and half of the group of no test participants 85.How different is the group of Nevada test participants from their South Pacific counterparts? A.The former shows a higher leukemia death rate than the comparison group. B.The former shows a lower leukemia death rate than the comparison group. C.The former shows a higher death rate than the latter. D.The former shows a lower death rate than the latter.

第1题

In only two decades Asian Americans have become the fastest-growing U. S. minority （少数民

In only two decades Asian Americans have become the fastest-growing U. S. minority (少数民族 ). As their children began moving up through the nation's schools, it became clear that a new class of academic achievers was emerging. Their achievements are reflected in the nation's best universities, where mathematics, science and engineering departments have taken on a decidedly Asian character. This special liking for mathematics and science is partly explained by the fact that Asian--American students who began their educations abroad arrived in the U. S. , with a solid grounding in mathematics but little or no knowledge of English. They are also influenced by the promise of a good job after college. Asians feel there will be less unfair treatment in areas like mathematics and science because they will be judged more objectively. And the return on the investment in education is more immediate in something like engineering than with an arts degree.

Most Asian-American students owe their success to the influence of parents who are determined that their children take full advantage of what the American educational system has to offer. Ah effective measure of parental attention is homework. Asian parents spend more time with their children than American parents do, and it helps. Many researchers also believe there is something in Asian culture that breeds success, such as ideals that stress family values and emphasize education.

Both explanations for academic success worry Asian Americans because of fears that they feed a typical racial (种族的) image. Many can remember when Chinese, Japanese and Filipino immigrants (移民) were the victims of social isolation. Indeed, it was not until 1952 that laws were laid down giving all Asian immigrants the right to citizenship.

While making tremendous achievements at college, Asian-American students ______.

A．feel they are mistreated because of limited knowledge of English

B．are afraid that their academic successes bear a strong Asian character

C．still worry about unfair treatment in society

D．generally feel it a shame to have to depend on their parents

点击查看答案

第2题

Near the end of a five-day tour of highly automated, high-tech Japanese factories, the Ame

rican visitor was overwhelmed and feeling a little inferior. Watching a string of gleaming stereo sets move down an assembly line, he turned to the plant manager and said, "Gosh, even your industrial design is better than ours.

"Ah, yes," replied the manager, "but America has treasures that Japan can never hope to possess."

"You mean our mineral wealth and bountiful farms？

"Ah, no. I was referring to Caltech and MIT."

America's scientific institutions--its technological universities and government laboratories--are the en vy of the world , producing ideas, devices and medicines that have made the U.S. prosperous, improved the lives of people around the globe and profoundly affected their perception of the world and the universe. This tremendous creativity is reflected in tile technical reports that are published in scientific journals throughout the world. Fully 35 % of them come from scientists doing their research at American institutions.

Yet American dominance can no longer be taken for granted. Many recent U. S. achievements and a wards stem in large measure from generous research grants of the past, and any weakening of government and industry commitment to support of basic research could in the next few decades cost the nation its scientific leadership. Some slipping is already divalent. In high-energy physics, where Americans once reigned supreme, Western Europe now spends roughly twice as much money as the U. S. Result. the major high-energy physics discoveries of tile past few years have been made not by Americans but by Europeans.

Even so, money alone cannot guarantee scientific supremacy. Freedom of inquiry, an intellectually stimulating environment and continuous recruitment of the best minds must accompany it. That combination has been achieved in many U.S. institutions--educational, governmental and industrial--but perhaps no where more successfully than at the National Institutes of Health, Bell Laboratories and Caltech.

America's technological universities and government laboratories are generally ______.

A．loved by scientists in other parts of the world

B．disliked by scientists in other parts of the world

C．admired by scientists in other parts of the world

D．jealous of scientists in other parts of the world

点击查看答案

第3题

The night is not what it was. Once, the Earth was cast half in shadow. Then came fire, can

dle, and light bulb, gradually drawing back the curtain of darkness. But a brighter world has its drawbacks.

An estimated 30 percent of outdoor lighting—plus even some indoor lighting—is wasted. Inefficient lighting costs U. S. about ＄10. 4 billion a year, according to Bob Gent of the International Dark-Sky Association, a nonprofit that aims to control light pollution.

Last year in Sydney, an estimated 2. 2 million Australians switched off their lights during “Earth Hour”, briefly reducing that city’s energy use by more than 10 percent. Motivated by such trends, more than two dozen cities worldwide went dim on March 29 this year in an hour-long demonstration.

A number of groups are trying to measure light pollution and assess its effects on the environment in the hope that people will reduce their own contribution to the problem. Scientists are trying to report how many stars we can see. In dark rural areas, about 2, 000 stars are typically visible at night, compared with“maybe five”in a bright city square—and about 5, 000 in centuries past.

People who are working while others are star-gazing may face the greatest risks. Nighttime exposure to white light can cause the growth of tumors (肿瘤) , experiments show. Two decades of research indicate that women who work night shifts have unusually high rates of breast cancer.

The word“drawbacks”in the first paragraph probably means_______.

A．benefits

B．interests

C．effects

D．problems

点击查看答案

第4题

In a few decades, artificial intelligence will surpass many of the abilities that we believe make us special.（）

点击查看答案

第5题

The country has （） too many wars in the past few decades; its people are longing for peace so much.

A.prevented from

B.resulted in

C.gone through

D.gone with

点击查看答案

第6题

It is obvious that UNESCO ______.A．is a company in FranceB．is a world organization in the

It is obvious that UNESCO ______.

A．is a company in France

B．is a world organization in the U. N.

C．works mainly at fighting against illiteracy

D．had many experts whose level of attainment is far from literacy

点击查看答案

第7题

Foreign investment is expanding rapidly all over the world. Most of the foreign companies

who have invested in the U. S. are Japanese and European. An example of the Japanese company in the U. S. is Toyota Motor Company, which produces cars. An example of a European company is Nestle of Switzerland. Nestle is a European company, but 99% of its in vestment are in other countries.

In Europe, there are many examples of foreign investment. Many American companies have invested in Europe, and many Japanese companies have also invested in Europe.

In recent years much foreign investment have shifted from the U. S. and Europe to Asia. Many companies from Japan, the United States and Europe are investing heavily in China. Other parts of Asia, such as India and the countries of Southeast Asia, are attracting a lot of American, Japanese and European investment as well.

What is the main topic of this passage？

A．Foreign investment in China.

B．Foreign investment in the U.S.

C．Foreign investment all over the world.

D．How to invest in other countries.

点击查看答案

第8题

Over the last few decades there has been a tremendous growth in information technolo

gy and its impact on everyday life. Complex software systems have become criticalto the operation of many systems in areas such as banking, communications, manufacturing,power generation, and transportation. Progress in computer science and accumulated experience with industrial production of software have led to the emergence of software engineering as a separate discipline. The software engineering discipline has been defined as"the application of systematic, disciplined, quantifiable approaches to the development,operation, and maintenance of software. " that is, the application of engineering to software.

点击查看答案

第9题

A.Seen B.which C.known D.physically E.toAs our knowledge of health and fitness increases

A.Seen B.which C.known D.physically E.to

As our knowledge of health and fitness increases,people are becoming more and moreinterested in not only taking care of themselves ___1,but mentally and spiritually as well.As aresult,many are turning ___2 more complete approaches to health,including less mainstream fitness methods such as yoga.

Yoga's origins lie in Hindu philosophy,___3 was developed thousands of years ago in India.Recent decades have ___4 yoga gain widespread acceptance as a method of staying in shape,as well as a way of handling stress.Pop singer Madonna and supermodel Christy Turlington are just two of the many celebrities ___5 to be strong advocates of yoga.

点击查看答案

第10题

听力原文：Henry Ford, the famous U. S. inventor and car manufacturer once said "The busines

听力原文： Henry Ford, the famous U. S. inventor and car manufacturer once said "The business of America is business. "By this he meant that the U. S. way of life is based on the values of the business world. A brief glimpse at a daily newspaper vividly shows how much people in the United States think about business. Business news can appear in every section. Most national news has an important financial aspect to it. Moreover, business news appears in some of the unlikeliest places. The world of arts and entertainment is often referred to as "the entertainment industry" or "show business."

The positive side of Henry Ford's statement can be seen in the prosperity that business has brought to U. S. life. One of the most important reasons so many people from all over the world come to live in the United States is the dream of a better job. However, the biggest companies are seen in opposition to labor. Throughout U. S. history working people have had to fight hard for higher wages, better working conditions, and the right to form. unions. Today, many of the old labor disputes are over, but there is still some employee anxiety. Downsizing--the laying off of thousands of workers to keep expenses low and profits high--creates feelings of insecurity for many.

The United States is a typical country

A．which encourages free trade at home and abroad.

B．where people's chief concern is how to make money.

C．where all businesses are managed scientifically.

D．which normally works according to the federal budget.

点击查看答案