Directions: Read the underlined sentences carefully, and then translate them into Chinese. You may check your answers after you finish them.

　　Passage One

　　As the horizons（范围） 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 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 must withstand temperatures as high as 1 600 degrees Fahrenheit, so aircraft designers had to the research metallurgist 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.

　　Passage Two

　　Thoughts from yesterday guide us toward tomorrow.

　　More than 2000 years ago, Caecilius Statius, a Roman slave who became famous as a playwright, observed, “we plant trees to benefit another generation.” His remark is as apt as it was when he made it and shows how thinkers of the past can still teach us something about the future.

　　George Bernard Show, for instance, made an even more perceptive remark. “We are made wise, not by the recollection of our past, but by the responsibility for our future.” This responsibility begins when we recognize that we ourselves create our future that the future is not something imposed upon us by fate or other forces beyond our control. We ourselves build the future both through what we do and what we do not do. Once we recognize our power over the future, we inevitably begin to anticipate the consequences of what we do and to do those things that will improve our future; in short, we begin to act wisely.

　　And our own responsibility for the future bears the promise of a better future world, because, as C. P. Snow, the novelist and philosopher, once remarked: “The sense of the future is behind all good policies. Unless we have it, we can give nothing either wise or decent to the world.” And our obligations must be more to the future than the past. Our greatest responsibility is to be good ancestors.

　　Passage Three

　　Criticism of research lays a significant foundation for future investigative work, but when students begin their own projects, they are likely to find that the standards of validity in field work are considerably more rigorous (严格的, 严厉的) than the standards for most library research.

　　When students are faces with the concrete problem of proof by field demonstration, they usually discover that many of the important relationships they may have criticized other researcher for failing to demonstrate are very elusive (难以理解的) indeed. They will find, if they submit an outline or questionnaire to their classmates for criticism, that other students make comments similar to some they themselves may have made in discussing previously published research. For example student researchers are likely to begin with a general question but find themselves forced to narrow its focus. They may learn that questions whose meanings seem perfectly biased (有偏见的) to someone else. They usually find that the formulation of good research questions is a much more subtle and frustrating task than is generally believed by those who have not actually attempted it.

　　Passage Four

　　Dry regions in the south western United States have become increasingly inviting playgrounds for the growing number of recreation seekers who own vehicles such as motorcycles or powered trail bikes and indulge (being crazy) in hill-climbing contests or in carving new trails in the desert. But recent scientific studies show that these off-road vehicles can cause damage to desert landscapes that has long-range effects on the area’s water-conserving characteristics and on the entire ecology (the scientific study of the pattern of relations of plants, animals, and people to each other and to their surroundings), both plant and animal. Research by scientists in the western Mojave Desert in California revealed that the compaction (压实) of the sandy dry soil resulting from the passage of just one motorcycle markedly reduced the infiltration (渗透) ability of the soil and created a stream of rain runoff water that eroded the hillside surface. In addition, the researchers discovered that the soil compaction caused by the off-road vehicles often killed native plant species and resulted in the invasion of different plant species within a few years. The native perennial (of a plant that lives for more than two years) species required many more years before they showed signs of returning. The scientists calculated that roughly a century would be required for the infiltration capacity of the Mojave soil to be restored after being compacted by vehicles.