单选题The passage indicates that

单选题According to the psychoanalyst Sigmund Freud, wisdom comes from the achievement of maturity.

单选题Smoking Since 1939, numerous studies have been conducted to determine whether smoking is a health hazard. The trend of the evidence has been consistent and indicates that there is a serious health risk. Research teams have conducted studies that show beyond all reasonable doubt that tobacco smoking is associated with a shortened life expectancy. Cigarette smoking is believed by most research workers in this field to be an important factor in the development of cancer of the lungs and cancer of the throat and is believed to be related to cancer of some other organs of the body. Male cigarette smokers have a higher death rate from heart disease than non-smoking males. Female smokers are thought to be less affected because they do not breathe in the smoke so deeply. Apart from statistics, it might be helpful to look at what tobacco does to the human body. Smoke is a mixture of gases, vaporized chemicals, minute particles of ash and other solids. There is also nicotine, which is powerful poison, and black tar. One point of concentration is where the air tube and bronchus divides. Most lung cancer begins at this point. Filters and low tar tobacco too are claimed to make smoking to some extent safer, but they can only slightly reduce, not eliminate the hazards.

单选题The doctors did not {{U}}reveal{{/U}} the truth to him. A. hide B. handle C. establish D. disclose

单选题Malnutrition "Much of the sickness and death attributed to the major communicable diseases is in fact caused by malnutrition which makes the body less able to withstand infections when they strike" , said Dr. Hiroshi Nakajima, Director-General of the World Health Organization (WHO). in his statement on the first day of the World Food Summit organized by the Food and Agriculture Organization of the United Nations in Rome, Italy, from 13 to 17 November, 1996. "At the same time, " he added, "in developing countries today, malnutrition is the cause of 174 million children under five years of age being underweight, and 230 million being stunted in their growth. Such figures represent deprivation, suffering and wasted human potential on a scale that is unacceptable from every point of view. Whether we think in terms of humanitarian concern, common justice or development needs, they demand a response, both from national governments and from international community. " At the end of January 1996, 98 countries had national plans of action for nutrition and 41 countries had one under preparation, in keeping with their commitments made at the International Conference on Nutrition in Rome in December 1992. The global situation, however. remains grim. Over 800 million people around the world still cannot meet basic needs for energy and protein, more than two thousand million people lack essential micronutrients, and hundreds of millions suffer from diseases caused by unsafe food and unbalanced diets. In sheer numbers, iron is the most prevalent micronutrient deficiency. Mainly women of reproduction age and children under five are affected by iron deficiency with prevalence hovering around 50% in developing countries. Among various regions in the world. it is South Asia which is hit hardest with prevalence reaching 80% in some countries. In infants and young children even mild anemia is associated with impaired intellectual as well as physical development. In older children and adults iron deficiency reduces work capacity and output. It also leads to increased accidents at work. While there is no single remedy, a combination of several preventive approaches is believed to work best. Dietary improvement includes consumption of iron and vitamin C-rich foods and foods of animal origin, and avoiding drinking tea or coffee with or soon after meals. Iron supplementation of foods, particularly of staple cereals, is practiced in a growing number of countries Iron supplementation is the most common approach, particularly for pregnant women.

单选题Tom found {{U}}damnably{{/U}} difficult, for three reasons.

单选题This table is strong and durable .

单选题The People's Republic of China was established in 1949.A. foundedB. startedC. improvedD. built

单选题Plant Gas Scientists have been studying natural sources of methane for decades but hadn"t regarded plants as a producer, notes Frank Keppler, a geochemist at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. Now Keppler and his colleagues find that plants, from grasses to trees, may also be sources of the greenhouse gas. This is really surprising, because most scientists assumed that methane production requires an oxygen-free environment. Previously, researchers had thought that it was impossible for plants to make significant amounts of the gas. They had assumed that, microbes need to be in environments without oxygen to produce methane. Methane is a greenhouse gas, like carbon dioxide. Gases such as methane and carbon dioxide trap heat in Earth"s atmosphere and contribute to global warming. In its experiments, Keppler"s team used sealed chambers that contained the same concentration of oxygen that Earth"s atmosphere has. They measured the amounts of methane that were released by both living plants; and dried plant material, such as fallen leaves. With the dried plants, the researchers took measurement at temperatures ranging from 30 degrees Celsius to 70 degrees Celsius. At 30 degrees Celsius, they found, a gram of dried plant material released up to 3 nanograms of methane per hour. (One nanogram is a billionth of a gram.) With every 10-degree rise in temperature, the amount of methane released each hour roughly doubled. Living plants growing at their normal temperatures released as much as 370 nanograms of methane per gram of plant tissue per hour. Methane emissions tripled when living and dead plant was exposed to sunlight. Because there was plenty of oxygen available, it"s unlikely that the types of bacteria that normally make methane were involved. Experiments on plants that were grown in water rather than soil also resulted in methane emissions. That"s another strong sign that the gas came from the plants and not soil microbes. The new finding is an "interesting observation," says Jennifer Y. King, a biogeochemist at the University of Minnesota in St. Paul. Because some types of soil microbes consume methane, they may prevent plant-produced methane from reaching the atmosphere. Field tests will be needed to assess the plant"s influence, she notes.

单选题______ more time, my paper would have been beRer.A. To giveB. If givingC. GivenD. Giving

单选题Helen Keller"s achievements as an author and lecturer were an inspiration to millions.

单选题The little gift grasped her mother's arm as she crossed the street. A. understood B. had a hold over C. took hold of D. left hold of

单选题You have to be patient if you want to sustain your position.

单选题He made a great show of reluctance, but finally accepted my offer.A. emotionB. unwillingnessC. angerD. postpone

单选题First Self Contained Heart Implanted A patient on the brink of death has received the world"s first self-contained artificial heart—a battery powered device about the size of a softball that runs without the need for wires, tubes or hoses sticking out of the chest. Two surgeons from the University of Louisville implanted the titanium and plastic pump during a seven-hour operation at Jewish Hospital Monday. The hospital said the patient was "awake and responsive" Tuesday and resting comfortably. It refused to release personal details. The patient had been expected to die within a month without the operation, and doctors said they expected the artificial heart to extend the person"s life by only a month. But the device is considered a major step toward improving the patient"s quality of life. The new pump, called AbioCor, is also a technological leap from the mechanical hearts used in the 1980s, which were attached by wires and tubes to bulky machinery outside the body. The most famous of those, the Jarvie-7, used air as a pumping device and was attached to an apparatus about the size of a washing machine. "I think it"s potentially a major step forward in the artificial heart development," said Dr. David Faxon, president of the American Heart Association. However, he said the dream of an implantable, permanent artificial heart is not yet a reality: "This is obviously an experimental device whose long-term success has to be demonstrated." Only about half of the 4,200 Americans on a waiting list for donor hearts received them last year, and most of the rest died. Some doctors, including Robert Higgins, chairman of cardiology at the Medical College of Virginia in Richmond, said artificial hearts are unlikely to replace donor hearts. "A donor heart in a good transplant can last 15 to 30 years," he said. "It"s going to be hard to replace that with a machine. " The AbilCor has a 2-pound pumping unit, and electronic controls that adjust the pumping speed based on the body"s needs. It is powered by a small battery pack worn outside the body that transmits current through the skin.

单选题We all think that Mary's husband is a very {{U}}boring{{/U}} person. A. shy B. stupid C. dull D. selfish

单选题Trading companies put up the money for the first English colonies in North America.

单选题"I didn"t mean to upset you," he said mildly .

单选题Tom felt so happy that he broke into song.A. burstB. blastedC. burnedD. blazed

单选题The dentist has decided to {{U}}take out{{/U}} the girl's bad tooth.