大学英语四级阅读理解练习 七

　　Directions: There are 4 passages in this part. Each passage is followed by some questions or unfinished statements. For each of them there are four choices marked A), B), C) and D). You should decide on the best choice and mark the corresponding letter on the Answer Sheet with a single line through the centre.
　　Questions 1 to 5 are based on the following passage:
　　As the horizons of science have expanded, two main groups of scientists have emerged. One is the pure scientist; the other, the applied scientist.
　　The pure or theoretical scientist does original research in order to understand the basic laws of nature that govern our world. The applied scientist adapts this knowledge to practical problems. Neither is more important than the other, however, for the two groups are very much related.
　　Sometimes, however, the applied scientist finds the "problems" for the theoretical scientist to work on. Let's take a particular problem of the aircraft industry: heat-resistant metals. Many of the metals and alloys（合金）which perform satisfactorily in a car cannot be used in a jet-propelled plane. New alloys must be used, because the jet engine operates at a much higher temperature than automobile engine. The turbine wheel in a turbojet （涡轮喷气发动机）must withstand temperatures as high as 1 600 degrees Fahrenheit, so aircraft designers had to turn to the research metallurgist（冶金学家）for the development of metals and alloys that would do the job in jet-propelled planes.
　　Dividing scientists into two groups pure and applied is only one broad way of classifying them, however. When scientific knowledge was very limited, there was no need for men to specialize. Today, with the great body of scientific knowledge, scientists specialize in many different fields. Within each field, there are even further subdivisions. The various sciences have become more and more interrelated until no one branch is entirely independent of the others. Many new specialties-geophysics and biochemistry, for example-have resulted from combining the knowledge of two or more sciences.
　　1. Concerning the relative importance of pure and applied scientists, the writer thinks that ________.
　　 A) applied scientists are more important
　　 B) pure scientists are more important
　　 C) neither are important
　　 D) both are equally important
　　2. "The horizons of science have expanded" means that ________.
　　 A) scientists can see further out into space
　　 B) science has developed more fields of endeavor（事业）
　　 C) the horizon changes size from year to year
　　 D) scientists have made a machine for enlarging the horizon
　　3. The work of the pure scientist is __________.
　　 A) working out laws for practical problems
　　 B) developing materials to be applied to practice
　　 C) doing original research to understand the nature of the universe
　　 D) applying the basic laws to practical problems
　　4. New alloys must be found to ___________.
　　 A) perform satisfactorily in a car
　　 B) withstand high temperatures in jet-propelled planes
　　 C) operate a jet-propelled plane
　　 D) resist heat in a car
　　5. Different fields of science_________.
　　 A) can be further divided.
　　 B) are independent of the others.
　　 C) are against the basic laws
　　 D) have become less interrelated