The increasing population is one of the most serious problems our world is facing now. New study shows that the world population will be 6,400,000,000 by 2050.

India will pass China as the world’s most populated country. China now has 1,300,000,000 people. The population should increase about ten percent by 2050. The United States will remain the third biggest nation whose population is close to 300,000,000 now. Because of immigration (移民) and low death rates among babies, its population will reach 420,000,000.

Between now and 2050, Niger will be the fastest growing country. The biggest decrease (减少) will be in Bulgaria. It is based on information from the United Nations.

And the study says most growth will take place in countries with young populations and traditionally large families. Nigeria and Japan will be different from each other. In Nigeria, almost half the people are under the age of fifteen. Few are over sixty-five. Nigerian women generally give birth about six times during their lives. Usually, a Japanese woman has one child. And today about twenty percent of Japanese are over the age of sixty-five.

根据短文内容，回答下列问题。

【1】Which country will have the largest population by 2050?

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【2】What’s the population of China by 2050?

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【3】Why will the population of the United States increase?

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【4】What country’s population will increase fast?

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【5】Which country will have more people than before, Nigeria or Japan?

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