No very satisfactory account of the mechanism that caused the formation of the ocean basins has yet been given. The traditional view supposes that the upper mantle of the earth behaves as a liquid when it is subjected to small forces for long periods and that differences in temperature under oceans and continents are sufficient to produce convection in the mantle of the earth with rising convection currents under the mid-ocean ridges and sinking currents under the continents. Theoretically, this convection would carry the continental plates along as though they were on a conveyor belt and would provide the forces needed to produce the split that occurs along the ridge. This view may be correct: it has the advantage that the currents are driven by temperature differences that themselves depend on the position of the continents. Such a back-coupling, in which the position of the moving plate has an impact on the forces that move it, could produce complicated and varying motions.On the other hand, the theory is implausible because convection does not normally occur along lines, and it certainly does not occur along lines broken by frequent offsets or changes in direction, as the ridge is. Also it is difficult to see how the theory applies to the plate between the Mid-Atlantic Ridge and the ridge in the Indian Ocean. This plate is growing on both sides, and since there is no intermediate trench, the two ridges must be moving apart. It would be odd if the rising convection currents kept exact pace with them. An alternative theory is that the sinking part of the plate, which is denser than the hotter surrounding mantle, pulls the rest of the plate after it. Again it is difficult to see how this applies to the ridge in the South Atlantic, where neither the African nor the American plate has a sinking part.Another possibility is that the sinking plate cools the neighboring mantle and produces convection currents that move the plates. This last theory is attractive because it gives some hope of explaining the enclosed seas, such as the Sea of Japan. These seas have a typical oceanic floor, except that the floor is overlaid by several kilometers of sediment. Their floors have probably been sinking for long periods. It seems possible that a sinking current of cooled mantle material on the upper side of the plate might be the cause of such deep basins. The enclosed seas are an important feature of the earth’s surface, and seriously require explanation in because, addition to the enclosed seas that are developing at present behind island arcs, there are a number of older ones of possibly similar origin, such as the Gulf of Mexico, the Black Sea, and perhaps the North Sea.

26.According to the traditional view of the origin of the ocean basins, which of the following is sufficient to move the continental plates?27.It can be inferred from the passage that, of the following, the deepest sediments would be found in the （ ） .28.According to the passage, which of the following are separated by a plate that is growing on both sides?29.The author refers to "conveyer belt" in Sentence 3, Paragraph 1, in order to（ ）.30.Which of the following titles would best describe the content of the passage?

A.Increases in sedimentation on ocean floors. B.Spreading of ocean trenches. C.Movement of mid-ocean ridges. D.Differences in temperature under oceans and continents.问题2： A.Indian Ocean B.Black Sea C.Mid-Atlantic D.South Atlantic问题3： A.The Pacific Ocean and the Sea of Japan. B.The South Atlantic Ridge and the North Sea Ridge. C.The Gulf of Mexico and the South Atlantic Ridge. D.The Mid-Atlantic Ridge and the Indian Ocean Ridge.问题4： A.illustrate the effects of convection in the mantle B.show how temperature differences depend on the positions of the continents C.demonstrate the linear nature of the Mid-Atlantic Ridge D.describe the complicated motions made possible by back-coupling问题5： A.A Description of the Oceans of the World B.Several Theories of Ocean Basin Formation C.The Traditional View of the Oceans D.Convection an

Accidents are caused; they don’t just happen. The reason may be easy to see: an overloaded tray, a shelf out of reach, a patch of ice on the road. But more often than not there is a chain of events leading up to the misfortune — frustration, tiredness or just bad temper — that show what the accident really is, a sort of attack on oneself.Road accidents, for example, happen frequently after a family quarrel, and we all know people who are accident-prone, so often at odds with themselves and the world that they seem to cause accidents for themselves and others.By definition, an accident is something you cannot predict or avoid, and the idea that the majority of road accidents are caused by criminally careless drivers. These show that most accidents involve ordinary drivers and motorists in a moment of carelessness or thoughtlessness.It is not always clear, either, what sort of conditions make people more likely to have an accident. For instance, the law requires all factories to take safety precautions and most companies have safety committees to make sure the regulations are observed, but still, every day in Britain, some forty thousand men and women are absent from work due to an accident. These accidents are largely the result of human error or misjudgment. Noise, fatigue, inattention and worry are possible factors which contribute to this. Doctors have found that those who drink too much, usually those who have a high anxiety level, run three times the normal risk of accidents.1.This passage might be taken from（ ）.2.The writer indicates that （ ）.3.Which of the following is not mentioned as a factor of accidents?4.‘‘Accident-prone’’ (Para. 2) probably means （ ）.5.Which of the following could serve as the best title for this passage?

Painter Frida Kahlo (1910―1954) often used harrowing images derived from her Mexican heritage to express suffering caused by a disabling accident and a stormy marriage. Suggesting much personal and emotional content, her works—many of them self-portraits—have been exhaustively psychoanalyzed, while their political content has been less studied. Yet Kahlo was an ardent political activist who in her art sought not only to explore her own roots, but also to champion Mexico’s struggle for an independent political and cultural identity.Kahlo was influenced by Marxism, which appealed to many intellectuals in the 1920s and 1930s, and by Mexican nationalism. Interest in Mexico’s culture and history had revived in the nineteenth century, and by the early 1900s, Mexican indigenista tendencies ranged from a violently anti-Spanish idealization of Aztec Mexico to an emphasis on contemporary Mexican Indians as the key to authentic Mexican culture. Mexican nationalism, reacting against contemporary United States political intervention in labor disputes as well as against past domination by Spain, identified the Aztecs as the last independent rulers of an indigenous political unit. Kahlo’s form of Mexicanidad, a romantic nationalism that focused upon traditional art uniting all indigenistas, revered the Aztecs as a powerful pre-Columbian society that had united a large area of the Middle Americas and that was thought to have been based on communal labor, the Marxist ideal.In her paintings, Kahlo repeatedly employed Aztec symbols, such as skeletons or bleeding hearts that were traditionally related to the emanation of life from death and light from darkness. These images of destruction coupled with creation speak not only to Kahlo’s personal battle for life, but also to the Mexican struggle to emerge as a nation—by implication, to emerge with the political and cultural strength admired in the Aztec civilization. Self-portrait on the Border between Mexico and the United States (1932), for example, shows Kahlo wearing a bone necklace, holding a Mexican flag, and standing between a highly industrialized United States and an agricultural, preindustrial Mexico. On the United States side are mechanistic and modem images such as smokestacks, light bulbs, and robots. In contrast, the organic and ancient symbols on the Mexican side—a blood-drenched Sun, lush vegetation, an Aztec sculpture, a pre-Columbian temple, and a skull alluding to those that lined the walls of Aztec temples—emphasize the interrelation of life, death, the earth, and the cosmos.Kahlo portrayed Aztec images in the folkloric style of traditional Mexican paintings, thereby heightening the clash between modem materialism and indigenous tradition; similarly, she favored planned economic development, but not at the expense of cultural identity. Her use of familiar symbols in a readily accessible style also served her goal of being popularly understood; in turn, Kahlo is viewed by some Mexicans as a mythic figure representative of nationalism itself.

31.Which one of the following best expresses the main point of the passage?32.Which one of the following statements concerning psychoanalytic and political interpretations of Kahlo's work would the author be most likely to agree?33.Which one of the following stances toward the United States does the passage mention as characterizing Mexican nationalists in the early twentieth century?34.In the context of the passage, which one of the following phrases could best be substituted for the word "romantic&

（ ）is forbidden in some states in the United States for religious reasons, while it is permitted in some other states.

The actress was very（ ） at the insulting question raised by her opponent at theconference.

The novel's unusual name（ ）me, so I bought one without hesitation.