【正确答案】
As is clearly portrayed in the chart above, the number of scholars returning from overseas kept increasing over the past years and rocketed to 50 thousand in 2004. People may wonder what is behind the amazing figure.
The foremost reasons for the tremendous increase can be illustrated as follows. To begin with, a set of preferential policies has contributed to the increase of the number. To attract the students studying overseas to return, our government has set up some preferential policies in terms of salaries, housing, choice of jobs, and children's education. Without these pohcies, the increase of the number is out of the question. What's more, the rapid development of our motherland has led to the increase of the number, too. Thanks to the reform and open policy, China's robust economy has laid a solid foundation for the rapid development of science and technology, which makes China a most inviting country to both Chinese at home and abroad and foreigners. Therefore, without the great leap of our mothedand over the past years, the increase of the scholars returning from overseas would be impossible.
In one word, our preferential policy and rapid development of our motherland are the root cause of the increase revealed in the chart above. We should try every means to attract more scholars to return so as to make more contributions to our motherland.

【答案解析】[解析] 文中开始段归纳了图表的意思，中间段分析了近年来留学回国人员持续增加的动因。结束段提出了作者的建议：应该尽力吸引更多的学成人员回国，为祖国的建设与发展贡献力量。