大学英语四级阅读理解练习 七

　　11. What does the author think about trying to find weakness in other people's research?
　　 A) It can be useful in planning future research.
　　 B) It may cause researchers to avoid publishing good works.
　　 C) It should only be attempted by experienced researchers.
　　 D) It is currently being done to excess.
　　12. According to the passage, what is one major criticism students often make of published research?
　　 A) The researchers failed to provide an appropriate summary.
　　 B) The researchers did not adequately establish the relationship involved.
　　 C) The research has not been written in an interesting way.
　　 D) The research has been done in unimportant fields.
　　13. How do students in class often react to another student's research?
　　 A) They offer unusually good suggestions for improving the work.
　　 B) They are especially critical of the quality of the research.
　　 C) They react the way they do to any other researcher.
　　 D) They show a lot of sympathy for the student researcher.
　　14. What do student researchers often learn when they discuss their work in class?
　　 A) Some students feel that the conclusions are too obvious.
　　 B) Other students rarely have objective comments about it.
　　 C) Other students do not believe the researchers did the work themselves.
　　 D) Some students do not understand the meaning of the researcher's questions.
　　15．Students may have to change their research projects because ________.
　　 A) Their time is very limited
　　 B) Their original questions are too broad
　　 C) Their teachers do not give adequate abvice
　　 D) Their budgets are too high
　　Questions 16 to 20 are based on the following passage:
　　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 （多年生植物）(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.
　　16.What is the main topic of the passage?
　　 A) Problems caused by recreational vehicle.
　　 B) Types of off-road vehicles.
　　 C) Plants of the southwestern desert.
　　 D) The increasing number of recreation seekers.
　　17.According to the passage, what is being damaged?
　　 A) Motorcycles.
　　 B) The desert landscape.
　　 C) Roads through the desert .
　　 D) New plant species.
　　18.According to the passage, the damage to plants is ______________.
　　 A) unnoticeable
　　 B) superficial
　　 C) long-lasting
　　 D) temporary
　　19.According to the passage, what happens when the soil is compacted?
　　 A) Little water flows through.
　　 B) Better roads are made.
　　 C) Water is conserved.
　　 D) Deserts are expanded.
　　20．What is happening to the desert hillsides?
　　 A) The topsoil is being eroded.
　　 B) The surface is being watered.
　　 C) There are fewer types of plants growing on them.
　　 D) There are fewer streams running through them.