问题是，这种权威就此在我们内心里扎下根来了吗？
佩皮当天在埃松省奥尔日河畔布雷蒂尼镇举行的新闻发布会上说，法国国营铁路公司的最初调查显示，出事列车的机车和车厢在今年6月29日进行了最后一次检查，没有发现任何机械异常。事故发生前通过该镇火车站的两列列车也没有显示任何异常现象。
Abstract：Investment is risky， and high risk means high ine. What kind of the portfolio is the most effective？ The rational investors always hope that the risk is low and the gain is large. Or， under the situation that the gain is equal， the risk is minimal. Markowitz put forward standardized model about the portfolio selection in 1959： mean - variance model. The model educes the optimal portfolio on the basis of a series of hypotheses. Then the evaluation indexes of the performance evaluation of the portfolio were proposed， including the Sharpe ratio， Treynor ratio and Jensen ratio， in order to measure the pros and cons of the investment activities. The paper selects 30 stocks， makes the empirical simulation research， gets two optimized portfolio， calculates their VAR value and their respective performance evaluation indexes：Sharpe index， Treynor index and Jensen index， and then makes a parative study.
1.糖尿病人吃加重病情
一、动手操作，调动课堂气氛