问题 多项选择题

关于可行域,下列描述正确的有( )。

A.可行域可能是平面上的一条线

B.可行域可能是平面上的一个区域

C.可行域就是有效边界

D.可行域由有效组合构成

答案

参考答案:A,B

解析: 当可供选择的证券有两种时,则可能的投资组合便是坐标系中的一条曲线;如可供选择的证券有三种,可能的投资组合便是坐标系中的一个区域;把排除那些被所有投资者认为是差的组合后余下的组合称为优先证券组合,而描绘在可行域中则是可行域的上边界部分,称为有效边界。因此C项中有效边界是可行域,但可行域不等同于有效边界。可行域的上边界部分,称为有效边界。对于可行域内部及下边界上的任意可行组合,均可以在有效边界上找到一个有效组合比它好。

阅读理解

阅读理解。

     Jenny Bowen, an American living in Beijing, has been selected as the only American to carry the 2008

Beijing Olympic torch on Chinese soil. She and seven other non-Chinese winners were from a pool of 262

applicants from 47 countries. 

     When Bowen runs with the Olympic torch, she will not only be representing the United States. She will

also be representing thousands of Chinese orphans, ABC news said.

     Bowen, a mother of two adopted (领养的) Chinese daughters, is executive director of Half the Sky

Foundation, an organization which was set up in 1998 and aims to enrich the lives and improve the future

for orphaned children in China.

     Nearly 10 years later, Bowen and Half the Sky Foundation have touched the lives of over 13,000 children.

Half the Sky Foundation is now present in 36 welfare institutions in 28 Chinese cities. About 4,000 children

are active in the program, which provides trained staff, educational tools, medical support and love for

orphans.

     Bowen hopes that running with the Olympic torch will help draw attention to the children in China. She

will be among the 19,400 runners who will carry the flame along an 85,000-mile,130-day route across five

continents. Beijing organizers say it will be the longest torch relay in the Olympic history.

     Like Bowen, the seven other non-Chinese winners, including a German engineer and a Venezuelan

designer, live in China. The other countries represented will be the Philippines, Colombia, India, Japan and

Russia.

     According to Olympic organizers, candidates (候选人) were selected based on their "love of Chinese

culture and history" and devotion to "communicating information about a real China to their native countries."

Each runner will carry the torch for 200 meters on Chinese soil.

1. Jenny Bowen will represent thousands of Chinese orphans mainly because _____. [ ]

A. she is an American orphan who lives in China.

B. she likes Chinese orphans very much.

C. she is director of the Half the Sky Foundation.

D. she has done a lot to the welfare of Chinese orphans.

2. Which of the following statements is false about Jenny Bowen? [ ]

A. She has been communicating information about the real China to the USA.

B. She is executive director of Half the Sky Foundation.

C. She loves Chinese culture and history very much.

D. She will carry the flame along an 85,000-mile route.

3. How many factors for selecting a candidate are mentioned in the passage? [ ]

A. One

B. Two

C. Three

D. Four

4. What is the passage mainly about? [ ]

A. Jenny Bowen, executive director of Half the Sky Foundation.

B. The longest torch relay in the Olympic history.

C. Eight non-Chinese persons to carry the Olympic torch in China.

D. A US woman to carry the Olympic torch in China.

多项选择题