GEOGRAPHY Analyze the document and answer the short-answer question that follows the document. In October 2006 the population of the United States reached 300 million people. Sandra Yin, a demographer at the Population Reference Bureau, describes the population of the United States and how it has grown. The United States is set to reach a milestone in October. It will become the third country-after China and India-to be home to at least 300 million people. Each 100 million has been added more quickly than the last. It took the United States more than 100 years to reach its first 100 million in 1915. After another 52 years, it reached 200 million in 1967. Less than 40 years later, it is set to hit the 300-million mark. Within another 37 years, we are projected to pass 400 million. Natural increase (the excess of births over deaths) drives most population growth (nearly 60 percent annually) in the United States. This relatively high natural increase sets the United States apart from other developed countries such as Sweden and the United Kingdom, where the excess of births over deaths accounts for less growth, respectively. Other developed countries such as Germany and Italy are seeing a natural decrease, or slightly more deaths than births. International migration accounts for about 40 percent of U.S. population growth. -Sandra Yin, "The United States at 300 Million," Population Reference Bureau. What is the main reason for the growth of population in the United States? What other factor influences the growth? GEOGRAPHY Analyze the document and answer the short-answer questions that follow the document. During Mao Zedong's rule in China, people studied his sayings for guidance on how to live and work. Some were quoted as proverbs. Here are a few of the many sayings that were reproduced and quoted. We must see to it that all our cadres [government workers] and all our people constantly bear in mind that ours is a big socialist country but an economically backward and poor one, and that this is a very great contradiction. To make China rich and strong needs several decades of intense effort, which will include, among other things, the effort to practise strict economy and combat waste, i.e., the policy of building up our country through diligence and frugality. The wealth of society is created by the workers, peasants and working intellectuals. If they take their destiny into their own hands, follow a Marxist-Leninist line and take an active attitude in solving problems instead of evading them, there will be no difficulty in the world which they cannot overcome. What is work? Work is struggle. There are difficulties and problems in those places for us to overcome and solve. We go there to work and struggle to overcome these difficulties. A good comrade is one who is more eager to go where the difficulties are greater. -Quotations from Chairman Mao Tse-tung [Mao Zedong]. What does Mao say to encourage his people to work for China's development?