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We can begin our discussion of “population as global issue” with what most persons mean when they discuss “the population problem”: too many people on earth and a too rapid increase in the number added each year. The facts are not in dispute, It was quite right to employ the analogy that likened demographic growth to “a long, thin powder fuse that burns steadily and haltingly until it finally reaches the charge and explodes.”
To understand the current situation, which is characterized by rapid increases in population, it is necessary to understand the history of population trends. Rapid growth is a comparatively recent phenomenon. Looking back at the 8,000 years of demographic history, we find that populations have been virtually stable or growing very slightly for most of human history. For most of our ancestors, life was hard, often nasty, and very short. There was high fertility
in most places, but this was usually balanced by high mortality. For most of human history, it was seldom the case that one in ten persons would live past forty, while infancy and childhood were especially risky periods. Often, societies were in clear danger of extinction because death rates could exceed their birthrates. Thus, the population problem throughout most of history was how to prevent extinction of the human race.
This pattern is important to notice. Not only does it put the current problems of demographic growth into a historical perspective, but it suggests that the cause of rapid increase in population in recent years is not a sudden enthusiasm for more children, but an improvement in the conditions that traditionally have caused high mortality.
Demographic history can be divided into two major periods: a time of long, slow growth which extended from about 8,000 BC.till approximately AD. 1650. In the first period of some 9600 years, the population increased from some 8
million to 500 million in 1650. Between 1650 and the present, the population has increased from 500 million to more than 4 billion. And it is estimated that by the year 2000 there will be 6.2 billion people throughout the world. One way to
appreciate this dramatic difference in such abstract numbers is to reduce the time frame to something that is more manageable. Between 8000BC and 1650, an average of only 50,000 persons was being added annually to the world’s population each year. At present, this number is added every six hours. The increase is about 80,000,000 persons annually.
1.Which of the following demographic growth pattern is most suitable for the
long thin powder fuse analogy?
A.A virtually stable or slightly decreasing period and then a sudden
explosion of population.
B.A slow growth for a long time and then a period of rapid, dramatic
increase.
C.Too many people on earth and a few rapid increase in the number added each
year.
D.A long period when death rates exceeds birthrates and then a short period
with higher fertility and lower mortality.
2.During the first period of demographic history, societies were often in
danger of extinction because___.
A.only one in ten persons could live past 40.
B.there was higher mortality than fertility in most places.
C.it was too dangerous to have babies due to the poor conditions.
D.our ancestors had little enthusiasm for more children.
3.Which statement is true about population increase?
A.There might be an increase of 2.2 billion persons from now to the year
2000.
B.About 50,000 babies are born every six hours at present.
C.Between 8000 BC and the present, the population increase is about
80,000,000 persons each year.
D.The population increased faster between 8000BC and 1650 than between 1650
and the present.
4.The author of the passage intends to___.
A.warn people against the population explosion in the near future.
B.compare the demographic growth pattern in the past with that after
1650.
C.find out the cause for rapid increase in population in recent years.
D.present us a clear and complete picture of the demographic growth.
5.The word “demographic” in the first paragraph means___.
A.statistics of human.
B.surroundings study.
C.accumulation of human.
D.development of human.
Scattered through the seas of the world are billions of tons of small plants
and animals called plankton. Most of these plants and animals are too small for
the human eye to see. They drift about lazily with the currents, providing a
basic food for many larger animals. Plankton has been described as the
equivalent of the grasses that grow on the dry land continents, and the
comparison is an appropriate one. In potential food value however, plankton far
outweighs that of the land grasses. One scientist has estimated that while
grasses of the world produce about 49 billion tons of valuable carbohydrates
each year. The sea’s plankton generates more than twice as much.
Despite its enormous food potential, little effort was made until recently to
farm plankton as we farm grasses on land. Now marine scientists have at last
begun to study this possibility, especially as the sea’s resources loom even
more important as a means of feeding an expanding world population.
No one yet has seriously suggested that “planktonburgers” may soon become
popular around the world. As a possible farmed supplementary food source,
however, plankton is gaining considerable interest among marine scientists.
One type of plankton that seems to have great harvest possibilities is a tiny
shrimplike creature called krill. Growing to two or three inches long, krill
provide the major food for the giant blue whale, the largest animal ever to
inhabit the Earth. Realizing that this whale may grow 100 feet and weigh 150
tons at maturity, it is not surprising that each one devours more than one ton
of krill daily.
Krill swim about just below the surface in huge schools sometimes miles wide,
mainly in the cold Antarctic. Because of their pink color, they often appear as
a solid reddish mass when viewed from a ship or from the air. Krill are very
high in food value. A pound of these crustaceans contains about 460
calories—about the same as shrimp or lobster, to which they are related.
If the krill can feed such huge creatures as whales, many scientists reason,
they must certainly be contenders as new food source for humans.
1.Which of the following best portrays the organization of the passage?
A.The author presents the advantages and disadvantages of plankton as a food
source.
B.The author quotes public opinion to support the argument for farming
plankton.
C.The author classifies the different food sources according to amount of
carbohydrate.
D.The author makes a general statement about plankton as a food source and
then moves to a specific example.
2.According to the passage, why is plankton regarded to be more valuable than
land grasses?
A.It is easier to cultivate.
B.It produces more carbohydrates.
C.It does not require soil.
D.It is more palatable.
3.Why does the author mention “planktonburgers”?
A.To describe the appearance of one type of plankton.
B.To illustrate how much plankton a whale consumes.
C.To suggest plankton as a possible food sources.
D.To compare the food values of beef and plankton.
4.What is mentioned as one conspicuous feature of krill?
A.They are the smallest marine animals.
B.They are pink in color.
C.They are similar in size to lobsters.
D.They have grass like bodies.
5.The author mentions all of the following as reasons why plankton could be
considered a human food source except that it is ___.
A.high in food value.
B.in abundant supply in the oceans.
C.an appropriate food for other animals.
D.free of chemicals and pollutants.
Passage 2
Questions 6 to 10 are based on the following passage:
When aluminum was first produced about a hundred and fifty years ago, it was
so difficult to separate form the ores in which it was found that its price was
higher than that of gold. The price remained high until a new process was
discovered for refining the metal with the aid of electricity approximately
three quarters of a century later. The new method was so much cheaper that
aluminum because practical for many purposes, one of which was making pots and
pans.
Aluminum is lightweight, rustproof and easily shaped into different forms. By
mixing it with other metals, scientists have been able to produce a variety of
alloys, some of which have the strength of steel but weigh only one third as
much.
Today, the uses of aluminum are innumerable. Perhaps its most important use
is in transportation. Aluminum is found in the engine of automobiles, in the
hulls of boats. It is also used in many parts of airplanes. In fact, the huge
“airbus” planes would probably never have been produced if aluminum did not
exist. By making vehicles lighter in weight aluminum has greatly reduced the
amount of fuel needed to move them, Aluminum is also being used extensively in
the building industry in some countries.
Since aluminum is such a versatile (多用的) metal, it is fortunate that bauxite
(铝土矿), which is one of its chief sources, is also one of the earth’s most
plentiful substances. As the source of aluminum is almost inexhaustible, we can
expect that more and more uses will be found for this versatile metal.
6. The price of aluminum was sharply reduced when people discovered a new
refining process with the aid of .
A. wind B. solar energy C. hydraulic power D. electricity
7. Aluminum is .
A. lightweight, rustproof but not easily shaped into different forms
B. heavyweight, rustproof and easily shaped into different forms
C. lightweight, rustproof and easily shaped into different forms
D. lightweight and easily shaped into different forms but it is easy to
become rusty
8. Which of the following is NOT true?
A. Aluminum is widely used in transportation.
B. Aluminum is also used in many parts of airplanes.
C. Aluminum is being used extensively in the building industry.
D. Aluminum is not used in its pure form.
9. Aluminum is found on earth mostly in the form of .
A. pure metal B. bauxite C. gold D. liquid
10. What is the passage talking about?
A. The features of aluminum and its functions. B. The process of
aluminum.
C. The discovery of aluminum. D. The promising future of aluminum.