单选题Naturally, in a group of animals as diverse as the snakes, and with so many varied enemies, there are numerous defensive reactions and devices. There is, however, one general pattern of hehaviour, in the presence of a suspected enemy the first reaction is to try to escape observation; if this fails, the next resort is flight to some inaccessible retreat, but if this is not possible, or is circumvented, various kinds of intimidatory gestures and warning devices arc brought into play ;in the last resort the snake attacks. This pattern varies with the circumstances; some stages may be omitted or combined unpredictably whilst some notoriously irascible species may dispense with all the preliminaries and attack almost at once, though seldom or never without some provocation. The difficulty is to know what constitutes provocation, a matter that is apt to be debatable in other fields! Amongst the factors that increase aggressiveness are hunger, the mating season and surprise, with the last mentioned the commonest ; when hunting for food or for mates, activity and the aggressive instinct are both at their peak, but it is when it is caught unawares that the normal chain of re- actions tends to become telescoped. Owing to their poor sense of hearing, snakes are very liable to be, quite literally, caught napping and a similar situation arises during their periods of temporary blindness just before sloughing begins. By far the greatest number of snake-bite accidents result from the unwitting disturbance of resting snakes, and this hazard is much increased with species that are well camouflaged and whose natural instinct is to trust to this concealment as their principal defence. As well as differences in aggressiveness between individuals of the same species according to the circumstances and conditions, there are also notable differences between species ,even closely allied species; and the reports of those who have been attacked may understandably be lacking in objectivity. So it is impossible to forecast, even in outline, how any encounter will develop. The Hamadryad, for example,is usually credited with being amongst the most aggressive of snakes ,and there are many accounts of unprovoked attacks ;yet on one occasion fourteen men and seven dogs passed and returned within two yards of a nest and no snake was seen although the fe- male, which guards the nest, could not have been far. away. One very well-known student of snakes once parked his car under some trees near Nairobi and on his return found a small green snake on it. Being preoccupied at the moment he gave it only a cursory glance and, thinking it was a common harmless tree-snake, bundled it unceremoniously into his pocket ;it was, as he later discovered to his horror, a young Green Mamba, but it made no attempt to bite despite the rough treatment it had received. The proportion of the snakes of the world that have some forms of procrypsis( i. e. resemblance to the background)is very high, but the frequency with which the resemblance results in accidents suggests that it is incorrect to regard it as primarily a "protective" device. There is every advantage to a predatory animal in being unobserved until its prey comes within striking distance, but it is distinctly hazardous to allow an enemy to approach closely with the hope ,but no certainty, of remaining undetected. The commonest type of proerypsis is the result of colours that harmonize with hose of the normal background, associated with patterns that disrupt the animal' s outline or produce "counter shading" whereby those parts of the body that will be seen in shadow and appear dark, are lighter in colour whilst highlight areas are dark-coloured.

单选题He argues that the policy has done little to ease joblessness, and has left the country ______.

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单选题The shortage of water became more ______this summer with the highest temperatures in 40 years.(2003年复旦大学考博试题)

单选题He grasped her by the throat and started to ______ the life out of her.

单选题What does the word "deprivation" mean ( Paragraph 3, Line 1)?

单选题Motorways are, no doubt the safest roads in Britain. Mile (41) mile, vehicle for vehicle, you are much (42) likely to be killed or seriously injured than on an ordinary road. On (43) hand, if you do have a serious accident on a motorway, fatalities are much more likely to (44) than in a comparable accident (45) on the roads. Motorways have no (46) bends,, no roundabouts or traffic lights and (47) speeds are much greater than on other roads. Though the 70 mph limit is (48) in force, it is often treated with the contempt that most drivers have for the 30 mph limit applying in built up areas in Britain. Added to this is the fact that motorway drivers seem to like traveling in groups with perhaps (49) ten metres between each vehicle. The resulting horrific pile-ups (50) vehicle stops for some reason mechanical failure, driver error and so on have become all (51) familiar through pictures in newspapers or on television. How (52) of these drivers realize that it takes a car about one hundred metres to brake to a stop (53) 70 mph? Drivers also seem to think that motorway driving gives them complete protection from the changing weather. (54) wet the road, whatever the visibility in mist or fog, on they (55) at ridiculous speeds oblivious of police warnings or speed restrictions (56) their journey comes to a conclusion. Perhaps one remedy (57) this motorway madness would be better driver education. At present, learner drivers are bared (58) motorways and are thus as far as this kind of driving is (59) thrown in at the deep end. However, much more efficient policing is required, (60) it is the duty of the police not only to enforce the law but also to protect the general public from its own foolishness.

单选题The European Parliament has banned the terms "Miss" and "Mrs" ______ they offend female members. A. as long as B. the moment C. so that D. in case

单选题Even after ten years her name {{U}}conjures up{{/U}} such beautiful memories.

单选题There is an old saying in English which goes, "Never put off until tomorrow What you can do today." A. look for it C. put it in place B. cancel it D. postpone it

单选题The company used so much coal that it has a train to ______ the delivery process.

单选题The excursion will give you an even deeper ______ into our language and culture.

单选题He collects ______ of all kinds of rocks and minerals. A. specimens B. timbers C. serpents D. trunks

单选题Although we decorated the room only six months ago, the paint on the ceiling is already______because of the damp.

单选题______ the passage of light, many new plastics are processed using technologies rivaling those used in the manufacture of computer chips.

单选题In a car engine, more ______ means better acceleration.

单选题Married people live "happily ever after" in fairy tales, but they do so less and less often in real life. I, like many of my friends, got married, divorced, and remarried. I suppose, to some people, I'm a failure. After all, I broke my first solemn promise to "love and cherish until death do us part. " But I feel that I'm finally a success. I learned from the mistakes I made in my first marriage. This time around, the ways my husband and I share our free time, make decision, and deal with problems are very different. I learned, first of all, not to be a clinging vine(依赖男子的妇女). In my first marriage, I felt the every moment we spent apart was wasted. If Ray wanted to go out to a bar with his friends to watch a football game, I felt rejected and talked him into staying home. I wouldn't accept an offer to go to a movie or join an exercise class if it meant that Ray would be home alone. I realize now that we were often angry with each other just because we spent too much time together. In contrast, my second husband and I spend some of our free time apart and try to have interests of our own. I have started playing racquet-ball at a health club, and David sometimes takes off to go to the local auto races with his friends. When we are together, we aren't bored with each other, our separate interests make us more interesting people. I learned not only to be apart sometimes but also to work together when it's time to make decisions. When Ray and I were married, I left all the important decisions to him. He decided how we would spend money, whether we should sell the car or fix it, and where to take a vacation. I know now that I went along with this so that I wouldn't have to take the responsibility when things went wrong. I could always end an argument by saying, "It was your fault!" With my second marriage, I am trying to be a full partner. We ask each other's opinions on major decisions and try to compromise if we disagree. If we make the wrong choice, we're equally guilty. When we rented an apartment, for example, we both had to take the blame for not noticing the drafty windows and the "no pets" clause in our lease. Maybe the most important thing I've learned is to be a grown-up about facing problems. David and I have made a vow to face our troubles like adults. If we're mad at each other or worried and upset, we say how we feel. Rather than hide behind our own misery, we talk about the problem until we discover how to fix it. Everybody argues or has to deal with the occasional crisis, but Ray and I always reacted like children to these stormy times. I would lock myself in the spare bedroom. Ray would stalk out of the house, slam the door, and race off in the car. Then I would cry and worry till he returned. I wish that my first marriage hadn't been the place where I learned how to make a relationship work, but at least I did learn. I feel better now about being an independent person, about making decisions, and about facing problems. My second marriage isn't perfect, but it doesn't have the deep flaws that made the first one fall apart.

单选题Scattered around the globe are more than 100 small regions of isolated volcanic activity known to geologists as hot spots. Unlike most of the world's volcanoes, they are not always found at the boundaries of the great drifting plates that make up the earth's surface; on the contrary, many of them lie deep in the interior of a plate. Most of the hot spots move only slowly, and in some cases the movement of the plates past them has left trails of dead volcanoes. The hot spots and their volcanic trails are milestones that mark the passage of the plates. That the plates are moving is not beyond dispute. Africa and South America, for example, are moving away from eath other as new material is injected into the sea floor between them. The complementary coastlines and certain geological features that seem to span the ocean are reminders of where the two continents were once joined. The relative motion of the plates carrying these continents has been constructed in detail, but the motion of one plate with respect to another cannot readily be translated into motion with respect to the earth's interior. It is not possible to determine whether both continents are moving in opposite directions or whether one continent is stationary and the other is drifting away from it. Hot spots, anchored in the deeper layers of the earth, provide the measuring instruments needed to resolve the question. From an analysis of the hot spot population it appears that the African plate is stationary and that it has not moved during the past 30 million years. The significance of hot spots is not confined to their role as a frame of reference. It now appears that they also have an important influence on the geophysical processes that propel the plates across the globe. When a continental plate come to rest over a hot spot, the material rising from deeper layer creates a broad dome. As the dome grows, it develops seed fissures(cracks); in at least a few cases the continent may break entirely along some of these fissures, so that the hot spot initiates the formation of a new ocean. Thus just as earlier theories have explained the mobility of the continents, so hot spots may explain their mutability(inconstant).