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问题 单项选择题

有效集以外的投资组合与有效边界上的组合相比，不包括（）。

A．相同的标准差和较低的期望报酬率

B．相同的期望报酬率和较高的标准差

C．较低的报酬率和较高的标准差

D．较低的标准差和较高报酬率

答案

参考答案：D

解析：

有效集以外的投资组合与有效边界上的组合相比，有三种情况：(1)相同的标准差和较低的期望报酬率；(2)相同的期望报酬率和较高的标准差；(3)较低的报酬率和较高的标准差。以上组合都是无效的。如果投资组合是无效的，可以通过改变投资比例转换到有效边界上的某个组合，以达到提高期望报酬率而不增加风险，或者降低风险而不降低期望报酬率的组合。

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Chuck Wall teaches management and human relations at Bakersfield College. He walked into class one day and told his students that their h   小题1:    was to perform one act of random(任意的) kindness. His students did not understand the assignment(任务), but the professor would not answer their questions. He e   小题2:   his students to find it out for themselves.

One week later, the students entered the classroom excited to s   小题3:  their stories. One student told of distributing blankets to the homeless, another had contacted a long, lost friend, and another student r  小题4:   that he had helped a dog to find its owner. Students were energized(激励) by the homework assignment and wanted other people to be kind too. W  小题5: the support of local businesses, the students made stickers to put on cars that invited people to do something k 小题6: for others. They sold the stickers and decided to donate the money to a center for the blind –not surprising as Professor Wall is blind.

Since then, s  小题7:  kindness activities have been organized in schools all over the world. Many schools organize a Random Acts of Kindness Week, a  小题8:  November 13, to celebrate World Kindness Day. Some schools use each day of Random Acts of Kindness Week to perform d 小题9: kind acts, such as making a new friend, helping someone, doing community service, or raising money for a charity. Students learn to c  小题10:  other people and think about how small actions can make the world a better place.
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一个长方体水池，长1.8米，宽1.3米，高0.3米占地面积是______平方米，其中放入深3/2米的水，池中有水______升．
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