粮食企业增值税退税:谁能帮我翻译三百个字？（力求准确！！）明天中午前需要。

The income of portfolio investment has uncertainty and great risk. To increase the income, we need to analyze the uncertain factors of market with related methods so that the market can be better forcasted to increase the certainty of investment.Based on entropy theory ,the investment decision method is investigated which has better simplicity and operation than tradition method of risking measurement and supply the vast investors a better analysis tool.Firstly,Some theories related closedly to portfolio market is presented. Secondly, the theories of the investment combination are presented, including investment analysis and portfolio theory.Meanwhile the problem how to find out a feasible investment decision method studied in the paper is put forward in order to instruct the investors to make investment decision more efficiently and make investment incomes and investment risks clear to them.Thirdly,from the tradational theory of investment decision combining the entropy theory,the optimization of investment combination is proved and computed, applying math tools and related computer software scientifically. At last, with the example of portfolio market,the application of entropy theory to portfolio investment market is proved and a summary is given to sum up.Furthermore,a prospect of the reserched problem is given.

Portfolio investment income uncertain risks. To increase revenue, we need to use tools or methods related to market uncertainty analysis to the market so they can better forecast to increase our investment in accuracy. This article is based on entropy theory using more traditional methods of investment decisions more risk measurement methods and operational simplicity, it provides a vast number of investors to better analytical tools. The first describes a number of closely related with the securities market theory, and then discussed the portfolio theory, including investment analysis, portfolio theory, this study also raised the question : How can we find a viable investment decision-making methods to enable investors to better, more effective investment decisions, make it possible to clear investment returns and investment risks. Then, this article from the traditional investment theory with decision-making, integration of entropy theory, the scientific use of mathematical tools and computer software related to portfolio optimization argument that the calculation. Finally, examples of the securities market, proving entropy theory in the stock market investment applications, and to sum up earlier, to be summarized and given to the subject of study prospects.