Read the passage carefully, then choose the correct answers.

   The dramatic growth of the world's population in the twentieth century was on a scale without parallel in human history. Most of this growth had occurred since 1950 and was known as the population 'explosion'. Between 1950 and 1980 the world population increased from 2.5 to over 4 billion, and by the end of the twenty century the figure had risen to about 6.6 billion. Growth of this size cannot continue indefinitely. Recent forecasts suggest that the total population will level out at between 10 and 15 billion in the mid twenty first century. Already there are encouraging signs that the rate of increase in many less developed countries is beginning to slow down.

The phrasal verb 'level out' in line 8 means ______.

Read the passage carefully, then choose the correct answers.

   No one knows the limits of population that the earth can support. Thomas Malthus, an English economist, developed a theory that became widely accepted in the nineteenth century. He suggested that because world population tended to increase more rapidly than the food supply, a continual strain was exerted upon available resources. Malthus cited wars, famines, epidemics, and other diseases as the usual limitations of population growth.

   With recent advances in science and technology, including improved agricultural methods and great strides in medicine, some of the limiting factors in population growth have been lessened, with obvious results.

   International organizations have put forward several recommendations to alleviate the problem of overpopulation, including an increase in food production, general economic development in target areas, and a decrease in birth rate. Most experts agree that it will be necessary to combine all three recommendations in an effort to affect a lasting solution.

It was suggested by Thomas Malthus that _______.

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   The world's population increased from 3 billion in 1959 to 6 billion by 1999, a doubling that occurred over 40 years. The Census Bureau's lasted projections imply that population growth will continue into the 21st century, although more slowly. The world's population is projected to grow from 6 billion in 1999 to 9 billion by 2042, an increase of 50 percent that will require 43 years.

   The world's population growth rate rose from about 1.5 percent per year from 1950 to 1951 to a peak of over 2 percent in the early 1960s due to reductions in mortality. Growth rates thereafter started to decline due to rising age at marriage as well as increasing availability and use of effective contraceptive methods. Note that changes in population growth have not always been steady. A dip in the growth rate from 1959 to 1960, for instance, was due to the Great Leap Forward in China. During that time, both natural disasters and decreased agricutural output in the wake of massive social reorganization caused China's death rate to rise sharply and its fertility rate to fall by almost half.

How many people did the world's population increase between 1959 and 1999?

Read the passage carefully, then choose the correct answers.

   The dramatic growth of the world's population in the twentieth century was on a scale without parallel in human history. Most of this growth had occurred since 1950 and was known as the population 'explosion'. Between 1950 and 1980 the world population increased from 2.5 to over 4 billion, and by the end of the twenty century the figure had risen to about 6.6 billion. Growth of this size cannot continue indefinitely. Recent forecasts suggest that the total population will level out at between 10 and 15 billion in the mid twenty first century. Already there are encouraging signs that the rate of increase in many less developed countries is beginning to slow down.

According to the passage, at no period in human history has there been ______.

Read the passage carefully, then choose the correct answers.

   No one knows the limits of population that the earth can support. Thomas Malthus, an English economist, developed a theory that became widely accepted in the nineteenth century. He suggested that because world population tended to increase more rapidly than the food supply, a continual strain was exerted upon available resources. Malthus cited wars, famines, epidemics, and other diseases as the usual limitations of population growth.

   With recent advances in science and technology, including improved agricultural methods and great strides in medicine, some of the limiting factors in population growth have been lessened, with obvious results.

   International organizations have put forward several recommendations to alleviate the problem of overpopulation, including an increase in food production, general economic development in target areas, and a decrease in birth rate. Most experts agree that it will be necessary to combine all three recommendations in an effort to affect a lasting solution.

What do most experts recommend in order to solve problems of overpopulation?

Read the passage carefully, then choose the correct answers.

   No one knows the limits of population that the earth can support. Thomas Malthus, an English economist, developed a theory that became widely accepted in the nineteenth century. He suggested that because world population tended to increase more rapidly than the food supply, a continual strain was exerted upon available resources. Malthus cited wars, famines, epidemics, and other diseases as the usual limitations of population growth.

   With recent advances in science and technology, including improved agricultural methods and great strides in medicine, some of the limiting factors in population growth have been lessened, with obvious results.

   International organizations have put forward several recommendations to alleviate the problem of overpopulation, including an increase in food production, general economic development in target areas, and a decrease in birth rate. Most experts agree that it will be necessary to combine all three recommendations in an effort to affect a lasting solution.

According to the passage, why has overpopulation been caused?

Read the passage carefully, then choose the correct answers.

   The dramatic growth of the world's population in the twentieth century was on a scale without parallel in human history. Most of this growth had occurred since 1950 and was known as the population 'explosion'. Between 1950 and 1980 the world population increased from 2.5 to over 4 billion, and by the end of the twenty century the figure had risen to about 6.6 billion. Growth of this size cannot continue indefinitely. Recent forecasts suggest that the total population will level out at between 10 and 15 billion in the mid twenty first century. Already there are encouraging signs that the rate of increase in many less developed countries is beginning to slow down.

It is pointed out in the passage that the increase in the world population ______.

Read the passage carefully, then choose the correct answers.

   The dramatic growth of the world's population in the twentieth century was on a scale without parallel in human history. Most of this growth had occurred since 1950 and was known as the population 'explosion'. Between 1950 and 1980 the world population increased from 2.5 to over 4 billion, and by the end of the twenty century the figure had risen to about 6.6 billion. Growth of this size cannot continue indefinitely. Recent forecasts suggest that the total population will level out at between 10 and 15 billion in the mid twenty first century. Already there are encouraging signs that the rate of increase in many less developed countries is beginning to slow down.

In 2000, the world's population was about ______.