[填空题]The growth of the population caused the change of its ______ Massive waves of immigration brought new ethnic groups into the country. Geographic and social mobility-- downward as well as upward--touched almost everyone.

[填空题]The growth of the population caused the change of its ______ Massive waves of immigration brought new ethnic groups into the country. Geographic and social mobility-- downward as well as upward--touched almost everyone.

[单项选择]

Malthusian fears that population growth will outstrip food supplies have been widely discounted as food production has kept well ahead of growing human numbers in the last half century. While population doubled, food supply tripled, and life expectancy increased from 46 in the 1950s to around 65 today. But more recently, some experts have once again been sounding the alarm about a possible food crisis.
The reason lies in the combined impact of many factors including climate change, forest denudation, land degradation, water shortage, declining oil supplies, species extinction, destruction of coastal ecosystems and the growing demands for a meat-rich diet from newly developed parts of the world.
At the root of all these problems has been the ruthless exploitation of the earth’s resources, fuelled by growing affluence in some parts of the world and desperate poverty in others. Between 1980 and 2000, global population rose from 4.4 billion to 6.1 billion, while
A. Mildly supportive
B. Somewhat indifferent
C. A little alarmed
D. Seemingly objective

[单项选择]Where is population growth happening（　）.
A. In all countries in the world.
B. In only a few countries.
C. In most countries.
D. Mainly in developed countries.

[填空题]The population growth mostly happens in cities of developing countries and more than 60 percent population live in cities.

[填空题]The highest rate of world population growth occurred in 1970.

[单项选择]Until recently, most population growth has occurred in relatively dense urban environments. In (31) words, even if we were witnessing rapid population growth, that would not mean that the (32) were filling in with people. (33) , the urban areas would tend to become more crowded. Historically, we find that people have moved to (34) the jobs were. Jobs were usually in ports or locations with many natural (35) . After transportation became relatively cheap, other geographical locations became (36) of economic activity. One factor that determines where people will move to, even when transportation becomes cheap, is (37) . And individuals working in cities (38) higher incomes than those working in (39) areas. Hence, population has tended until the 1970s to (40) in our major urban centers.
Recently population has (41) out of the Northeast to the South and to the West for the more pleasant climates. If people di
A. sparsely
B. densely
C. scarcely
D. meagerly