英語四級考試將在12月17日舉行，大家備考得如何了呢? 以下是小編整理的關於英語四級閱讀理解訓練及答案，供大家備考。
英語四級閱讀理解
Questions 61-65 are based on the following passage.
A useful definition of an air pollutantis a compound added directly or indirectly by humans to the atmospherein suchquantities as to affect humans, animals, vegetation, or material adversely (有害地.. Air pollution requires avery flexibledefinition that permits continuous change. When the first air pollution lawswere established inEngland in the fourteenth century, air pollutants werelimited to compounds that could be seen or smelled—a farcry (懸殊的差別. from the extensive list of harmful substances known today. Astechnology has developed andknowledge of the health aspects of variouschemicals has increased, the list of air pollutants has lengthened. Inthefuture, even water vapor (水蒸氣. might be consideredan air pollutant under certain conditions.
Many of the more important airpollutants, such as sulfur oxides, carbon monoxide, and nitrogen oxides,arefound in nature. As the Earth developed, the concentrations ( 濃度. of these pollutants were altered byvariouschemical reactions; they became components in biogeochemical (生物地球化學的. cycles. These serve as an airpurification scheme by allowing thecompounds to move from the air to the water or soil. On a global basis,naturesoutput of these compounds dwarfs that resulting from human activities. However,human productionusually occurs in a localized area, such as a city.
In this localized region, human outputmay be dominant and may temporarily overload the natural purificationscheme ofthe cycles. The result is an increased concentration of noxious ( 有害的. chemicals in the air. Theconcentrations atwhich the adverse effects appear will be greater than the concentrations thatthe pollutants wouldhave in the absence of human activities. The actualconcentration need not be large for a substance to be apollutant; in fact thenumerical value tells us little until we know how much of an increase thisrepresents over the concentration that would occur naturally in the area. Forexample, sulfur dioxide has detectable health effects at0.08 parts per million(ppm., which is about 400 times its natural on monoxide, however, has a naturallevel of 0.1 ppm and is not usually apollutant until its level reaches about 15 ppm.
61、It can be inferred from thefirst paragraph that _________
r vapor is an air pollutant in localized areas
definition of air pollution will continue to change
C.a substance becomes an air pollutant only in cities
air pollutants today can be seen or smelled
62、In what way can naturalpollutants play an important role in controlling air pollution?
function as part of a purification process.
are dwarfed by the pollutants produced by human activities.
are less harmful to living beings than are other pollutants.
have existed since the Earth developed.
63、According to the passage,the numerical value Of the concentration level of a substance is only useful if
other substances in the area are known
is a localized area
can be calculated quickly
naturally occurring level is also known
64、Which of the following isbest supported by the passage?
effectively control pollution, local government should regularlyrevise the air pollution laws.
of the most important steps in preserving natural lands is tobetter enforce air pollution laws.
ntists should be consulted in order to establish uniform limitsfor all air pollutants.
n activities have great impact on air pollution.
65、The passage mainlydiscusses _________
economic impact on air pollution
much damage air pollutants can cause
constitutes an air pollutant
quantity of compounds added to the atmosphere
答案解析：
61-65 BADDB
相關擴充套件：大學四級閱讀理解
Newdays,a standard for measuring power has changes foretell a new standard for measuring longer will a nations political influence be based solely on the strength of its military forces. Of course, military effectiveness will remain a primary primary measure of political influence is also closely tied to industrial competitiveness. Its often said that without its military the Soviet Union would really be a third-world nation. The new standard of opwer and influence that is evolving now places more emphasis on the ability of a country to compete effectively in the economic markets of the world.
America must recognize this new course of events. Our success in shaping world events over the past 40 years has been the direct result of our ability to adapt technology and to take advantage of the capabilities of our people for the purpose of maintaining peace. Our industrial prowess over most of this period was unchallenged. It is ironic that it is just this prowess that has enabled other countries to prosper and in turn to threaten our industrial leadership.
The competitiveness of Americas industrial base is an issue bigger than the Department of Defense and is going to require the efforts of the major institutional forces in our society-government,industry,and education. That is not to say that the Defense Department will not be a strong force in the process because we will. But we simply cannot be, nor should we be, looked upon by others as the savior of American industry.
1. Now a nations political influence depends on _________.
a. the strength of its military forces
b. its ability to compete in industry
c. economic markets
d. both a and b
2. The Soviet Union was not listed as a third-world nation just because of _________.
a. its powerful military forces
b. its vast land
c. its industrial competitiveness
d. its contributions to world peace
3. The author indicates that ______ is threatening American political power.
a. other countries
b. the declining industrial base
c. a new standard for measuring power
d. less advanced technology
4. America succeeded in shaping world events over past 40 years probably because of ___________.
a. its ability to adapt technology
b. its ability to take advantage of the capabilities of its people
c. its ability to compete in the world markets
d. both a and b
5. The purpose of writing this article is __________.
a. to draw the readers attention to a new standard for measuring power
b. to demonstrate American political influence in the world
c. to emphasize that efforts must be made to strengthen the declining industrial base
d. to show American industrial prowess
答案：dabdc
