单选题When once you have caught the disease, you are {{U}}immune{{/U}} from it for the rest of your life.

单选题A result of nuclear explosion,fallout is the descent of minute particles of radioactive materiaI through the atmosphere.

单选题France has kept intimate links with its former African territories. A．friendly B．private C．strong D．secret

单选题Gambling is lawful in Nevada.

单选题 Avalanche and Its Safety An avalanche is a sudden and rapid flow of snow, often mixed with air and water, down a mountainside. Avalanches are {{U}} {{U}} 1 {{/U}} {{/U}}the biggest dangers in the mountains for both life and property. All avalanches are caused by an over-burden of material, typically snowpack, that is too massive and unstable for the slope {{U}} {{U}} 2 {{/U}} {{/U}}supports it. Determining the critical load, the amount of over-burden which is {{U}} {{U}} 3 {{/U}} {{/U}}to cause an avalanche, {{U}} {{U}} 4 {{/U}} {{/U}}a complex task involving the evaluation of a number of factors. Terrain slopes flatter than 25 degrees or steeper than 60 degrees typically have a low {{U}} {{U}} 5 {{/U}} {{/U}}of avalanche. Snow does not {{U}} {{U}} 6 {{/U}} {{/U}}significantly on steep slopes; also, snow does not {{U}} {{U}} 7 {{/U}} {{/U}}easily on flat slopes. Human-triggered avalanches have the greatest incidence when the snow's angle of rest is {{U}} {{U}} 8 {{/U}} {{/U}}35 degrees and 45 degrees; the critical angle, the angle at which the human incidence of avalanches is greatest, is 38 degrees. The rule of thumb is. A slope that is {{U}} {{U}} 9 {{/U}} {{/U}}enough to hold snow but steep enough to ski has the potential to generate an avalanche, regardless of the angle. Additionally, avalanche risk increases with {{U}} {{U}} 10 {{/U}} {{/U}}that is, the more a slope is disturbed by skiers, the more likely it is that an avalanche will occur. Due to the complexity of the subject, winter travelling in the backcountry is never 100% safe. Good avalanche safety is a continuous {{U}} {{U}} 11 {{/U}} {{/U}}, including route selection and examination of the snowpack, weather {{U}} {{U}} 12 {{/U}} {{/U}}, and human factors. Several well-known good habits can also {{U}} {{U}} 13 {{/U}} {{/U}}the risk. If local authorities issue avalanche risk reports, they should be considered and all warnings should be paid {{U}} {{U}} 14 {{/U}} {{/U}}to. Never follow in the tracks of others without your own evaluations; snow conditions are almost certain to have changed since they were made. Observe the terrain and note obvious avalanche paths where plants are {{U}} {{U}} 15 {{/U}} {{/U}}or damaged. Avoid traveling below others who might trigger an avalanche.

单选题I wonder what your aim in life is.

单选题The little boy was so fascinated by the mighty river that he would spend hours sitting on its bank and gazing at the passing boats and rafts. A. very strong B. very long C. very great D. very fast

单选题Major manufacturers have been using "quality circle" with undeniable success for more them two decades.A. 100 yearsB. 20 yearsC. 50 yearsD. 10 years

单选题12 You should have blended the butter with the sugar thoroughly.

单选题The reason for their unusual behavior remains a puzzle .

单选题We propose to furnish our own house according to our own taste.A. displayB. fixC. paintD. decorate

单选题She is notable for her generous contribution for the relief of the poor.A. guiltB. accusedC. famousD. responsible

单选题Tebbut's own product, called Brainstorm, is a {{U}}sophisticated{{/U}} software 'ideas organizer' that is cheap, easy to use and quite helpful.

单选题Prolonging Human Life Prolonging human life has increased the size of the human population. Many people alive today would have died of childhood diseases if they had been born 100 years ago. Because more people live longer, there are more people around at any given time. In fact, it is a decrease in death rates, not an increase in birthrates, that has led to the population explosion. Prolonging human life has also increased the dependency load. In all societies, people who are disabled or too young or too old to work are dependent on the rest of society to provide for them. In hunting and gathering cultures, old people who could not keep up might be left behind to die. In times of famine, infants might be allowed to die because they could not survive if their parents starved, whereas if the parents survived they could have another child. In most contemporary societies, people feel a moral obligation to keep people alive whether they can work or not. We have a great many people today who live past the age at which they want to work or are able to work; we also have rules which require people to retire at a certain age. Unless these people were able to save money for their retirement, somebody else must support them. In the United States many retired people five on social security checks which are so little that they must live in near poverty. Older people have more illness than young or middle-aged people; unless they have wealth or private or government insurance, they must often "go on welfare" if they have a serious illness. When older people become senile or too weak and ill to care for themselves, they create grave problems for their families. In the past and in some traditional cultures, they would be cared for at home until they died. Today, with most members of a household working or in school, there is often no one at home who can care for a sick or weak person. To meet this need, a great many nursing homes and convalescent hospitals have been built. These are often profit-making organizations, although some are sponsored by religious and other nonprofit groups. While a few of these institutions are good, most of them are simply " dumping grounds" for the dying in which "care" is given by poorly paid, overworked, and underskilled personnel.

单选题His idea to solve the problem is really original .

单选题It can be seen from the passage that most diabetics are ignorant of

单选题Latin might once have been {{U}}claimed{{/U}} as the most suitable of possible international language.

单选题{{B}}第三篇{{/B}} If you want to stay young, sit down and have a good think. This is the research finding of a team of Japanese doctors, who say that most of our brains are not getting enough exercises-and as a result, we are ageing unnecessarily soon. Professor Taiju Matsuzawa wanted to find out why otherwise healthy farmers in northern Japan appeared to be losing their ability to think and reason at a relatively early age, and how the process of ageing could be slowed down. With a team of colleagues at Tokyo National University, he set about measuring brain volumes of a thousand people of different ages and varying occupations. Computer technology enabled the researchers to obtain precise measurements of the volume of the front and side sections of the brain, which relate to intellect(智能)and emotion, and determine the human character. (The rear section of the brain, which controls functions like eating and breathing, does not contract with age, and one can continue living without intellectual or emotional faculties〈功能〉.) Contraction of front and side parts-as cells die off was observed in some subjects in their thirties, but it was still not evident in some sixty and seventy-year-olds. Matsuzawa's concluded from his tests that there is a simple remedy to the contraction normally associated with age-using the head. The findings show in general terms that contraction of the brain begins sooner in people in the country than in the towns. Those least at risk, says Matsuzawa, are lawyers, followed by university professors and doctors. White collar workers doing routine work in government officers are, however, as likely to have shrinking brains as the farm worker, bus driver and shop assistant. Matsuzawa's findings show that thinking can prevent the brain from shrinking. Blood must circulate properly in the head to supply the fresh oxygen the brain cells need. "The best way to maintain good blood circulation is through using the brain," he says, "Think hard and engage in conversation. Don't rely on pocket calculators."

单选题The standards set four years ago in Seoul will be far below the athletes' {{U}}capabilities{{/U}} now.

单选题There is always excitement at the Olympic Games when an athlete Ubreaks/U a record.