2011年12月英语四级模拟试卷及答案分析(5)_第5页

　　Section C
　　Directions: In this section, you will hear a passage three times. When the passage is read for the first time, you should listen carefully for its general idea. When the passage is read for the second time, you are required to fill in the blanks numbered from 36 to 43 with the exact words you have just heard. For blanks numbered from 44 to 46 you are required to fill in the missing information. For these blank, you can either use the exact words you have just heard or write down the main points in your own words. Finally, when the passage is read for the third time, you should check what you have written.
　　Scientists have developed a new cancer drug. So far, they have tested it only on (36) ________ animals. The drug is designed to (37) ________ and kill cancer cells but not healthy cells.
　　First, the drug enters the cancer and destroys the supply of blood. Then it releases (38) ________ to destroy the cancer cells.
　　Researchers at the Massachusetts Institute of Technology in Cambridge carried out the study. The (39) ________ appeared in Nature (40) ________. A school news release called the drug an "anti-cancer smart bomb."
　　Ram Sasisekharan is a professor at M.I.T. He says his team had to (41) ________ three problems. They had to find a way to destroy the blood vessels, then to (42) ________ the growth of new ones. But they also needed the blood vessels to supply chemicals to destroy the cancer.
　　So, the researchers designed a two-part "nanocell". The cell is (43) ________ in nanometers, or one thousand millionth of a meter. (44) ________________________.
　　The scientists say it was small enough to pass through the blood vessels of the cancer, but it was too big to enter normal blood vessels. The surface of the nanocells also helped them to avoid natural defenses.
　　(45) ________________________. That cut off the blood supply and trapped the nanocell inside the cancer. Then, the nanocell slowly released chemotherapy drugs to kill the cancer cells.
　　(46) ________________________.

　　Part IV Reading Comprehension (Reading in Depth) (25 minutes)
　　Section A
　　Directions: In this section, there is a short passage with 5 questions or incomplete statements. Read the passage carefully. Then answer the questions or complete statements in the fewest possible words. Please write your answers on Answer Sheet 2.
　　Many of the most damaging and life threatening types of weather-torrential rains, severe thunderstorms, and tornadoes-begin quickly, strike suddenly, and disappear rapidly, destroying small regions while leaving neighboring areas untouched. Such event as a tornado struck the northeastern section of Edmonton, Alberta, in July 1987. Total damages from the tornado exceeded $250 million, the highest ever for any Canadian storm.
　　Conventional computer models of the atmosphere have limited value in predicting short lived local storms like the Edmonton tornado, because the available weather data are generally not detailed enough to allow computers to study carefully the subtly atmospheric changes that come before these storms. In most nations, for example, weather-balloon observations are taken just once every twelve hours at locations typically separated by hundreds of miles. With such limited data, conventional forecasting models do a much better job predicting general weather conditions over large regions than they do forecasting specific local events.
　　Until recently, the observation intensive approach needed for accurate, very short-range forecasts, or "Nowcasts", was not feasible. The cost of equipping and operating many thousands of conventional weather stations was extremely high, and the difficulties involved in rapidly collecting and processing the raw weather data from such a network were hard to overcome. Fortunately, scientific and technological advances have overcome most of these problems. Radar systems, automated weather instruments, and satellites are all capable of making detailed, nearly continuous observation over large regions at a relatively low cost. Communications satellites can transmit data around the world cheaply and instantaneously, and modern computers can quickly compile and analyze this large volume of weather information. Meteorologists (气象学者) and computer scientists now work together to design computer programs and video equipment capable of transforming raw weather data into words, symbols, and vivid graphic displays that forecasters can interpret easily and quickly. As meteorologists have begun using these new technologies in weather forecasting offices, Nowcasting is becoming a reality.
　　47. It can be inferred from the passage that the value of damages from torrential rains, severe thunderstorms and tornadoes is ________________________.
　　48. Why do conventional models of the atmosphere fail to predict such a short-lived tornado?
　　___________________________________________________________________________.
　　49. It can be inferred from the passage that conventional forecasting models are now mostly used for ________________________.
　　50. What does "Nowcasts" mean according to the passage?
　　___________________________________________________________________________.
　　51. According to the passage, what makes "Nowcasting" a reality?
　　___________________________________________________________________________.