[单项选择]After thirty years of television, people have become "speed watchers". Consequently, if the camera lingers, the interest of the audience ______.
A. broadens
B. begins
C. varies
D. flags

[单项选择]After thirty years of television, people have become "speed watchers". Consequently, if the camera lingers, the interest of the audience ______.
A. broadens
B. begins
C. varies
D. flags

[单项选择]Why more and more people became interested in becoming computer programmers
A. Because the job is very interesting.
B. Because they can get well paid in this profession.
C. Because it takes no great efforts to learn to do it.
D. Because of the high social status of the professionals.

[单项选择]After people have learned that magnets attract things, centuries passed ______ they took note of the fact that magnets sometimes also repel things.
A. before
B. until
C. after
D. since

[单项选择]Only in recent years have people begun to realize the importance of wildlife protection.
A. 直到近年来人们才越来越意识到保护野生动物的重要性。
B. 只是在最近几年里人们才开始发现并保护了很多重要的野生动物。
C. 直到近年来人们才开始意识到保护野生环境的紧迫性。
D. 直到近年来人们才开始了解保护野生动物的重要性。

[单项选择]After years of research, scientists have ______ the virus that is responsible for the disease.
A. recognized
B. identified
C. guaranteed
D. notified

[单项选择]After years of negotiation, an international agreement to conserve （） species and ecosystems has finally been changed.
A. ventilated
B. imperiled
C. utilized
D. modified

[单项选择]After years of strenuous work, the scientists are on the __________.of a great discovery of human gene.
A. domain
B. premise
C. threshold
D. pretext

[单项选择]After years of research, Charles Drew devised a procedure for preserving plasma.
A. transporting
B. saving
C. reusing
D. labeling

[单项选择]Fifteen years have passed since we graduated from the middle school.I have found she has（）.
A. some white hair
B. much white hair
C. a few white hairs
D. a little white hair

[单项选择]How many years have they known each other

[单项选择]He developed a ______ attitude after years of frustration in his career.
A. sneaking
B. disgusted
C. drastic
D. cynical

[单项选择]

Text 4 Although, recent years have seen substantial reductions in noxious pollutants from individual motor vehicles, the number of such vehicles has been steadily increasing. Consequently, more than 100 cities in the U. S. still have levels of carbon monoxide, particulate matter, and ozone that exceed legally established limits. There is a growing realization that the only effective way to achieve further reduction in vehicle emissions—short of a massive shift away from the private automobile—is to replace conventional diesel fuel and gasoline with cleaner-burning fuel such as compressed natural gas, liquefied petroleum gas, ethanol, or methanol. All of these alternatives are carbon-based fuels whose molecules are smaller and simpler than those of gasoline. These molecules burn more cleanly than gasoline, in part because they have fewer, if any, carbon-carbon bonds, and the hydrocarbons they do emit are less likely to generate ozone. The combustion of larger mo
A. be somewhat lighter in total body weight than a conventional vehicle fueled with gasoline
B. have a larger and more powerful engine than a conventional vehicle fueled with gasoline
C. average more miles per gallon than a "gasoline alone" vehicle fueled with methanol
D. have a larger and heavier fuel tank than a "gasoline alone" vehicle fueled with methanol