单选题Each plant and animal by natural tendency, ______ far more seeds and eggs and seedlings and young, than is necessary to maintain ______ population.

单选题It is no ______ that his car was seen near the bank at the time of the robbery.

单选题In general, lasers operate by creating an intense amount of light and energy which is then converted into heat and used to control bleeding or destroy diseased tissue.

单选题Tile rivers and streams of the Amazon basin teem with life, and the forest canopy resonates with the cries of birds and monkeys and the whines of insects.

单选题His major task is to integrate the work of various bureaus under the ministry.

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单选题The mood of complacency in the European Union (EU) is driven largely by the recovery in France and Germany and the imminent launch of economic and monetary union. But two (51) recent developments challenge the notion (52) the EU can remain immune from the shocks occurring around emerging markets. The first phenomenon is that the financial (53) are occurring simultaneously and in many instances are mutually reinforcing. Contagion is no longer a (54) ; it is a fact of life. The erosion of market confidence (55) with a second phenomenon: the emergence of a political (56) in Moscow, Tokyo, Washington, and Bonn. The EU and (57) 15 member states have contributed generously through IMF packages and technical aids to strengthen domestic banking supervision in Asia. But (58) the highest level, EU leaders have shown themselves driven by domestic political (59) All the difficult negotiations over EU enlargement, (60) , were put off until after the German election in Sept ember.

单选题Parkinson"s disease, first described in the early 1800s by British physician James Parkinson as "shaking palsy", is among the most prevalent neurological disorders. According to the United Nations, at least four million people worldwide have it; in North America, estimates run from 500,000 to one million, with about 50,000 diagnosed every year. These figures are expected to double by 2040 as the world"s elderly population grows; indeed, Parkinson"s and other neurodegenerative illnesses common in the elderly (such as Alzheimer"s and amyotrophic lateral sclerosis) are on their way to overtaking cancer as a leading cause of death. But the disease is not entirely one of the aged: 50 percent of patients acquire it after age 60; the other half are affected before then. Furthermore, better diagnosis has made experts increasingly aware that the disorder can attack those younger than 40. So far researchers and clinicians have found no way to slow, stop or prevent Parkinson"s. Although treatments do exist-including drugs and deep-brain stimulation-these therapies alleviate symptoms, not causes. In recent years, however, several promising developments have occurred. In particular, investigators who study the role proteins play have linked miscreant proteins to genetic underpinnings of the disease. Such findings are feeding optimism that fresh angles of attack can be identified. As its 19th-century name suggests--and as many people know from the educational efforts of prominent Parkinson"s sufferers such as Janet Reno, Muhammad Ali and Michael J. Fox--the disease is characterized by movement disorders. Tremor in the hands, arms and elsewhere, limb rigidity, slowness of movement, and impaired balance and coordination are among the disease"s hallmarks. In addition, some patients have trouble walking, talking, sleeping, urinating and performing sexually. These impairments result from neurons dying. Although the victim cells are many and found throughout the brain, those producing the neurotransmitter dopamine in a region called the substantia nigra are particularly hard-hit. These dopaminergic nerve cells are key components of the basal ganglia, a complex circuit deep within the brain that fine-tunes and co-ordinates movement. Initially the brain can function normally as it loses dopaminergic neurons in the supstantia nigra, even though it cannot replace the dead cells. But when half or more of these specialized cells disappear, the brain can no longer cover for them. The deficit then produces the same effect that losing air traffic control does at a major airport. Delays, false starts, cancellations and, ultimately, chaos pervade as parts of the brain involved in motor control--the thalamus, basal ganglia and cerebral cortex--no longer function as an integrated and orchestrated unit.

单选题In buying a suit, a difference of ten cents in price is Unegligible/U.

单选题New data has______that the damage to the ozone layer is not confined to the southern hemisphere.

单选题There is a ______ difference in meaning, between the words surroundings and environment. A. gentle B. subtle C. feeble D. humble

单选题One of the consequences of advanced cognitive ability has been the emergence of cultural life.

单选题As we have seen, propaganda can appeal to us by arousing our emotions or ______, our attention from the real issues at hand.

单选题Countries within the European Community grant certain commercial ______ to each other. A. advantages B. benefits C. privileges D. subsidies

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单选题As an ______ part of China, Kongkong returned to the embrace of its motherland in July, 1997.

单选题Sound moves from its source to the ear by wave like fluctuations in air pressure, something like the peaks and troughs or the lowest point of ocean waves. One way to keep from hearing sound is to use ear plugs. Another way is to cancel out the sound with anti-sound. Using a noise maker controlled by a microprocessor, engineers have produced sound waves that are half a wavelength out of phase with those of the noise to be quieted--each peak is matched to a trough, and vice versa. Once the researchers have recorded the offending sound, a microprocessor calculates the amplitude and wavelength of sound that will cancel out the highest and lowest points of the noise. It then produces an electric current that is amplified and fed to a loudspeaker, which produces anti-sound and wipes out the noise. If the anti-sound goes out of synchronization, a microphone picks up the leftover sound and sends it back to the microprocessor, which changes the phase of the anti-sound just enough to cause complete silence. The research team has concentrated on eliminating low-frequency noise from ship engines, which causes fatigue that can impair the efficiency and alertness of the crew, and may mask the warning sounds of alarm and fog signals.

单选题Contestants who do not{{U}} comply with {{/U}}the regulations will be disqualified.