单选题Trees are so common arid quiet that we pay them little mind. What, for instance, should we answer when asked to name the biggest living thing Earth has ever seen? Dinosaurs? Blue whales? No, the largest sequoias in northern California weigh more than six blue whales. The tallest redwoods and Australian eucalyptus trees tower more than 300 feet high, three times the length of the greatest dinosaur. (71) Some bristlecone pine trees in the American West are more than 4, 000 years old, seedlings at the time the Egyptians were building the Pyramids. Trees sustain our lives and our planet in a thousand practical ways. This morning at breakfast—in your wood-framed house, on your wooden kitchen table—you might have enjoyed orange juice or a grapefruit. Both come to use from trees. Over your French toast you may have sprinkled cinnamon and nutmeg, the powdered bark and nuts of tropical trees. That quart of maple syrup on your table was boiled down from roughly 10 gallons of sap from a sugar-maple tree. (72) Do you like chocolate, almonds, cola beverages.'? Cocoa beans, almonds and kola nuts are tree products. Frees do more than mule life pleasant; they make life possible. Trees get water through their roots and, primarily through their leaves, they draw carbon dioxide from the air. Then, with the action of sunlight on cells containing chlorophyll and other materials, chemical reactions occur, and oxygen is released. (73) Photosynthesis also produces glucose, a type of sugar. Trees convert some of the glucose to starch, which they use for energy storage. The cellulose fiber we call wood is made of thousands of glucose molecules linked into giant chains that no longer taste sweet. (74) The ancient Greeks, for example, treated pain with a tea made by boiling willow leaves and bark, a tea modern scientists now know contains silicon, a precursor of acetylsalicylic acid—aspirin. (75) More recently, researchers isolated and synthesized the chemical ginkgolide from the tree for use in treating asthma, toxic shock and other ills.A. For centuries, the Chinese have derived medicines from the ginkgo tree.B. Through photosynthesis, an acre of trees produces enough oxygen to sustain three humans.C. As scientists unlock the secrets of trees, they uncover surprising tacts.D. Trees have always been green machines, producing substances that humans learned to use.E. You think, at 150 or more years, giant tortoises can live a long time?F. And the morning newspaper was printed on the processed wood pulp we call paper.

单选题With his brows knitted, the doctor {{U}}contemplated{{/U}} the difficult operation he had to perform.

单选题The report sets out strict inspection procedures to ensure that recommendations are properly Uimplemented/U.

单选题It is postulated that population trends have an effect on economic fluctuations. A. deducted B. assumed C. decreed D. challenged

单选题The most damning thing that can be said about the world"s hest-endowed and richest country is that it is not only not the leader in health status, but that it is so low in the ranks of the nations. The United States ranks 18th among nations of the world in male life expectancy at birth, 9th in female life expectancy at birth, and 12th in infant mortality. More importantly, huge variations are evident in health status in the United States from one place to the next and from one group to the next. The forces that affect health can be aggregated into four groupings that lends to analysis of all health problems. Clearly the largest aggregate of forces resides in the person"s environment. His own behavior, in part derived from his experiences with his environment, is the next greatest force affecting his health. Medical care services, treated as separate from other environmental factors because of the special interest we have in them, make a modest contribution to health status. Finally the contributions of heredity to health are difficult to judge. We are templated at conception as to our basic weaknesses and strengths, but many hereditary attributes never become manifest because of environmental and behavioral forces which act before the genetic forces come to maturity, and other hereditary attributes are increasingly being palliated by medical care. No other country spends what we do per capita for medical care. The care available is among the best technically, even if used too lavishly and thus dangerously, but none of the countries which stand above us in health status have such a high proportion of medically disenfranchised persons. Given the evidence that medical care is not that valuable and access to care not that bad, it seems most unlikely that our bad showing is caused by the significant proportion who are poorly served. Other hypotheses have greater explanatory power: excessive poverty, both actual and relative, and excessive affluence. Excessive poverty is probably more prevalent in the U.S. than in any of the countries that have a better infant mortality rate and female life expectancy at birth. This is probably true also for all but four or five of the countries with a longer male life expectancy. In the notably poor countries that exceed us in male survival, difficult living conditions are a more accepted way of life and in several of them, a good basic diet, basic medical care and basic education, and lifelong employment opportunities are an everyday fact of life. In the U. S. a national unemployment level of 10 percent may be 40 percent in the ghetto(黑人居住地) while less than 4 percent elsewhere. The countries that have surpassed us in health do not have such severe or entrenched problems. Nor are such a high proportion of their people involved in them. Excessive affluence is not so obvious a cause of ill health, but, at least until recently, few other nations could afford such unhealthful ways of living. Excessive intake of animal protein and fats, dangerous imbibing of alcohol and use of tobacco and drugs (prescribed and proscribed), and dangerous recreational sports and driving habits are all possible only because of affluence. Our heritage, desires, opportunities, and our machismo, combined with the relatively low cost of bad foods and speedy vehicles, make us particularly vulnerable to our affluence. And those who are not affluent try harder. Our unacceptable health status, then, will not be improved appreciably by expanded medical resources nor by their redistribution so much as by a general attempt to improve the quality of life for all.

单选题Some confusion has ______ about who can join the association.

单选题Small, pink and very ugly. Hardly the qualities of a star, but they describe the deformed mouse that was the media darling at a recent science exhibition in Beijing. With a complex tissue structure in the shape of a human ear grafted on to its back, the rosy rodent was a stunning symbol of the serious strides China is making in the field of biotechnology. China is fast applying the latest life-science techniques learned from the West to aggressively pursue genome research. It's establishing its own centers of technical excellence to build a scientific base to compete directly with the United States and Europe. With a plentiful supply of smart young scientists at home and lots of interest abroad biotechnology is on the brink of a boom in China. And in the view of foreign scientists, Beijing is playing a clever hand, maximizing the opportunities open to them. For the moment, the cooperation exists mostly with Europe and the U. S.. But Asia's other biotech leaders, Japan, Singapore and Korea, also are recognizing China's potential as an attractive low-cost base to conduct research. These partnerships and China's advancement in the field of biotechnology—could help benefit the rest of Asia: China's rapid progress in improving crop yields will address food-security concerns in the region. In addition, China is more likely to focus on developing cheap technology that its predominantly poor population—and those of other Asian countries—can afford. There remain, however, serious barriers to the development of a strong biotech industry. Among them are a poor domestic legal framework, weak enforcement of intellectual-property rights and loose adherence to international standards. China is a signatory of the International Bio Safely Protocol, which should mean adherence to global standards governing the conduct of field trials. But some observers are skeptical. "The regulations look good, but I haven't met one scientist who believes they are being fully adhered to",says a European science analyst. If shortcuts are taken, then some of the recent scientific achievements trumpeted in the official press may never make it to market. But no matter how strict lab test are, other problems lie in wait. For example, there is a number of tasks it would take years to fulfill in the patents office, says one lawyer, leaving innovators with little protection if they take a product to market in China.

单选题{{B}}Passage 3{{/B}} The Internet is a global network that connects other computer networks, together with software and protocols for controlling the movement of data. The Internet, often referred to as "the Net", was initiated in 1969 by a group of universities and private research groups funded by the US Department of Defense. It now covers almost every country in the world. Its organization is informal and deliberately nonpolitical; its controllers tend to concentrate on technical aspects rather than on administrative control. The Internet offers users a number of basic services including data transfer, electronic mail, and the ability to access information in remote databases. A notable feature is the existence of user groups, which allow people to exchange information and debate specific subjects of interest. In addition, there are a number of high-level services. For example, MBONE allows the transmission of messages to more than one destination. It is used in videoconferencing. The World Wide Web, known as "the Web", is another high level Internet service, developed in the 1990s in Geneva. It is a service for distributing multimedia information, including graphics, pictures, sounds, and video as well as text. A feature of the World Wide Web is that it allows links to other related documents elsewhere on the Internet. Documents for publication on the Web are presented in a form known as HTML (hypertext mark up language). This allows a specification of the page layout and typography as it will appear on the screen. It also allows the inclusion of active links to other documents. Generally, these appear on the screen display as highlighted text or as additional icons. Typically, the user can use a mouse to "click" on one of these points to load and view a related document. Many commercial and public organizations now have their own Web site (specified by an address code) and publish a "home page", giving information about the organization. Up to the mid-1990s, the major users of the Internet were academic and research or ganizations. This has begun to change rapidly with individual home users linking in through commercial access providers and with a growing interest by companies in using the Internet for publicity, sales, and as a medium for electronic publishing. At the same time, there are problems with the flow of information across national borders, bringing in debates about copyright protection, data protection, the publication of pornography, and ultimately political control and censorship.

单选题There changes have not been sufficient to______the losses. A. stem B. stimulate C. cause D. compensate

单选题At the same time, medical and social science research began to indicate that retirement itself had detrimental effects.

单选题{{B}}Passage Three{{/B}} The traditional appeal of the income tax has come from its wide acceptance as a lair tax. closely related to an individual's ability to pay. For many gears the income tax provided large federal income without imposing heavy burdens on the great majority of people. By the mid-20th century, however, serious criticisms of tax loopholes were heard concerted attempts at reform resulted only in a more complex and eroded tax base. The situation worsened in the 1970s, as rising inflation pushed people into higher tax brackets although their incomes were barely keeping pace with rising prices. This pressure further eroded public confidence in the fairness of the income tax; at the same time it created strong incentives to utilize tax shelters and other loopholes, as well as to conceal off-the-record income. Built-in inflation adjustments were adopted, first by a number of states and then in 1985 by the federal government. Income tax policy is inevitably controversial because it rests essentially on judgments that must be constantly reconsidered as social values change. The complex task of working out the many reductions and exclusions to be allowed from income because they either make for greater fairness among taxpayers or promote worthy social goals (such as charitable contributions) bone of the most difficult and politically sensitive problems faced by governments. Another major area of dispute is whether wages and salaries should be taxed the same way as business profits or investment income. While some countries and a few U. S. states explicitly apply separate sets of rules to the measurement of different kinds of taxable income, others, like most U. S. state governments, seek to treat all sources of income in the same way. Even so, dissimilarities inevitably arise. Some costs of earning income are more readily deducted (扣除) from business and self-employment earnings than they are from wages and salaries. Inflation, by eroding the value of capital, distorts the measurement of income from that source. Complex adjustments to the tax law could in principle eliminate these imbalances, but most countries have preferred simpler, more arbitrary solutions.

单选题Obviously, no teacher has ______ patience. Even Larry, who is always kind and tolerant, lost his temper on that particular occasion. A. definite B. spectacular C. infinite D. composed

单选题 She kept to her point tenaciously, and would not give way.

单选题A rocket might miss its target, by a "wide margin". This means the rocket missed the target ______.

单选题By the end of the year 2004, he ______ in the army for 40 years.

单选题It"s difficult for my father to ______ without a cane.

单选题Which unit belongs to the Customary System?

单选题What useful information can be drawn from the passage by a chronic Lyme patient?

单选题Should the death penalty be______?(2004年上海理工大学考博试题)