单选题How much of the world's land surface is at risk of becoming desert?

单选题The physician had to visit his patient six ______ days before the patient could be considered in a fair condition. A. consequent B. consecutive C. consistent D. conservative

单选题The amending Treaty on European Union can become law only if there is ______ agreement to this effect.(2003年中国科学院考博试题)

单选题How can personal income tax be levied to ______ as many as possible while at the same time ensuring state finances do not suffer too much? A. interest B. benefit C. profit D. concern

单选题Since she was alone, she opened the door ______, leaving the chain lock fastened. A.warily B.consciously C.audaciously D.recklessly

单选题Thousands of years ago man used handy rocks for his surgical operations. Later he used sharp bone or horn, metal knives and more recently, rubber and plastic. And that was where we stuck, in surgical instrument terms, for many years. In the 1960s a new tool was developed, one which was, first of all, to be of great practical use to the armed forces and industry, but which was also, in time, to revolutionize the art and science of surgery. The tool is the laser and it is being used by more and more surgeons all over the world, for a very large number of different complaints. The word laser means: Light Amplification by Stimulated Emission of Light. As we all know, light is hot; any source of light ——from the sun itself down to a humble match burning ——will give warmth. But light is usually spread out over a wide area. The light in a laser beam, however, is concentrated. This means that a light with no more power than that produced by an ordinary electric light bulb becomes intensely strong as it is concentrated to a pinpoint-sized beam. Experiments with these pinpoint beams showed researchers that different energy sources produce beams that have a particular effect on certain living cells. It is now possible for eye surgeons to operate on the back of the human eye without harming the front of the eye, simply by passing a laser beam right through the eyeball. No knives, no stitches (刀口缝合), no unwanted damage ——a true surgical wonder. Operations which once left patients exhausted and in need of long periods of recovery time now leave them feeling relaxed and comfortable. So much more difficult operations can now be tried. The rapid development of laser techniques in the past ten years has made it clear that the future is likely to be very exciting. Perhaps some cancers will be treated with laser in a way that makes surgery not only safer but more effective. Altogether, tomorrow may see more and more information coming to light on the diseases which can be treated medically.

单选题Chemistry did not emerge as: science until after the scientific revolution in 17th century and then only rather slowly and laboriously. But chemical knowledge is as old as history, being almost entirely concerned with the practical arts of living. Cooking is essentially a chemical process; so is the melting of metals and the administration of drugs and potions. This basic chemical knowledge, which was applied in most cases as a rule of thumb, was nevertheless dependent on previous experiment. It also served to stimulate a fundamental curiosity about the processes themselves. New information was always being gained as artisans improved techniques to gain better results. The development of a scientific approach to chemistry was, however, hampered by several factors. The most serious problem was the vast range of material available and the consequent difficulty of organizing it into some system. In addition, there were social and intellectual difficulties. Chemistry is nothing if not practical: those who practice it must use their hands, they must have a certain practical aptitude. Yet in many ancient civilizations, practical tasks were primarily the province of a slave population. The thinker or philosopher stood apart from this mundane world, where the practical arts appeared to lack any intellectual content or interest. The final problem for early chemical science was the element of secrecy. Experts in specific trades had developed their own techniques and guarded their knowledge to prevent others from stealing their livelihood. Another factor that contributed to secrecy was the esoteric nature of the knowledge of alchemists, who were trying to transform base metals into gold or were concerned with the hunt for the elixir (炼金药). That would bestow the blessing of eternal life. In one sense, the second of these was the more serious impediment because the records of the chemical processes that early alchemists had discovered were often written down in symbolic language intelligible to very few or in symbols that were purposely obscure.

单选题The number of stay-at-home fathers reached a record high last year, new figures show, as families saw a______ in female breadwinners. (2013年北京大学考博试题)

单选题The little boy couldn't resist the ______to take the money on the table.

单选题In 1844, Charles Sturt, a British soldier and colonial administrator, made an expedition ______ a supposed inland sea; his party penetrated more than 1000 miles northward, almost to the center of Australia. A. in quest of B. with regard to C. in favor of D. by way of

单选题The continuous rain set______the harvesting of wheat by two weeks.

单选题Very few scientists ______ completely new answers to the world's problems. A. come up with B. come out C. come round D. come up to

单选题Men commit______motoring offences as women, according to the Home Office figures. A. nine times of B. as nine times C. nine times that of D. nine time as many

单选题American fans have selected Yao in a vote for the All-Star game ______ the legendary O'Neal, who ______ the "Great Wall" at the weekend as the Rockets beat the Los Angeles Lakers.

单选题This watch is ______ to all the other watches on the market

单选题{{B}}Passage 2{{/B}} Analysts have had their go at humor, and I have read sortie of this interpretative literature, but without being greatly instructed. Humor can be dissected, as a frog can, but the thing dies in the process and the innards (内在部分) are discouraging to any but the pure scientific mind. In a newsreel theatre the other day I saw a picture of a man who had developed the soap bubble to a higher point than it had ever before reached. He had become the ace soap bubble blower of America, had perfected the business of blowing bubbles, refined it, doubled it, squared it, and had even worked himself up into a convenient lather. The effect was not pretty. Some of the bubbles were too big to be beautiful, and the blower was always jumping into them or out of them, or playing some sort of unattractive trick with them. It was, if anything, a rather repulsive sight. Humor is a little like that: it won't stand much blowing up, and it won't stand much poking. It has a certain fragility, an evasiveness, which one had best respect. Essentially, it is a complete mystery. A human frame convulsed with laughter, and the laughter becoming mysterious and uncontrollable, is as far out of balance as one shaken with the hiccoughs or in the throes of a sneezing fit. One of the things commonly said about humorists is that they are really very sad people—clowns with a breaking heart. There is some truth in it, but it is badly stated. It would be more accurate, I think, to say that there is a deep vein of melancholy running through everyone's life and that the humorist, perhaps more sensible of it than some others, compensates for it actively and positively. Humorists fatten on trouble. They have always made trouble pay. They struggle along with a good will and endure pain cheerfully, knowing how well it will serve them in the sweet by and by. You find them wrestling with foreign languages, fighting folding ironing boards and swollen drainpipes, suffering the terrible discomfort of tight boot (or as Josh Billings wittily called them, "tire boots"). They pour out their sorrows profitably, in a form that is not quite a fiction not quite a fact either. Beneath the sparking surface of these dilemmas flows the strong tide of human woe. Practically everyone is a manic depressive of sorts, with his up moments and his down moments, and you certainly don't have to be a humorist to taste the sadness of situation and mood. But there is often a rather fine line between laughing and crying, and if a humorous piece of writing brings a person to the point where his emotional responses are untrustworthy and seem likely to break over into the opposite realm, it is because humor, like poetry, has an extra content. It plays close to the big hot fire, which is Truth, and sometimes the reader feels the heat.

单选题One of the wrong notions about science is that many scientific discoveries have come about ______. A. accordingly B. accidentally C. artificially D. additionally