问题 单项选择题

某企业需要采用甲、乙、丙三种原材料生产Ⅰ、Ⅱ两种产品。生产中,两种产品所需原材料数量、单位产品可获得利润以及企业现有原材料数如表所示

  产品(吨) 现有原材料(吨)
资源 1 1 4
4 3 12
1 3 6
单位利润(万元/吨) 9 12
则公司可以获得的最大利润是 (66) 万元。取得最大利润时,原材料 (67) 尚有剩余。

A.甲

B.乙

C.丙

D.乙和丙

答案

参考答案:A

解析:根据吴祈宗主编的《运筹学》中的内容,本题考查最优化线性规划方法。根据题意,可以建立线性规划模型:
假设x1,x2分别是两种产品的生产数量,则
Maxz=9x1+12x2
[*]
运用《运筹学》中介绍的单纯形方法,求解线性规划模型可以得到:[*]。说明最优生产方案为生产Ⅰ2吨,生产Ⅱ4/3吨,获得最大利润为
由于得到最优解以后,将[*]代入约束条件,第一个约束条件x1+x2≤4小于号成立,第二个约束条件4x2+3x2≤12等号成立,第三个约束条件x2+3x2≤6等号成立,说明此时乙、丙两种资源均使用完,而甲材料仅使用了10/3吨,剩余2/3吨。
此题最简单的方法是建立线性规划模型后,采用高中解析几何中的图解法在直角坐标系中完成。

写作题

读写任务

阅读下面的短文, 然后按照要求写一篇150词左右的英语短文。

Dear Jane,

     My dear daughter, do you know how shocked I was to be told that you have chosen to be a

journalist? A short, slim and weak girl like you should take such a job as her career! Do you know

how worried I am? Do you still remember your dear Uncle Danny, my handsome and wise younger

brother? The insightful and strong willed journalist honored in the press circle, was sent to report

what was happening in the Middle East. He left with a strong sense of duty but never returned home.

We did not get the news until 4 months after his death, and his ashes until 2 years later. I was crying

my heart out with you in my arms...

     You are only 18 years old and never old enough to make such a hasty decision for your life. Let’ s

try to see what you have. You are learning as one of the top students in a school famous all over the

country. You can choose to go to an ideal university without sitting for the exam. You are now one of

the masters among your contemporaries. Just think of 4 years later when you graduate from an

excellent university and, I am sure, many good jobs are waiting for you, but not to be a journalist. I

am so proud of you and you have been my hope in my heart since your father’ s death. I would not

like to be alone when my only daughter finishes college and works for a job that totally fails to give me

a sense of security.

     Jane, think about it carefully.

                                                                                                                                Sincerely,

                                                                                                                                  Mom

【写作内容】

假设你是Jane. , 请你给母亲回信。

1. 以约30个词概括来信的大意;

2. 然后以约120个词说服你的母亲让你当记者. , 并包括以下要点:

(1)当记者是你的理想;

(2)记者工作的重要性;

(3)让母亲不要担心。

【写作要求】

1. 作文中可使用自己的亲身经历或虚构的故事. , 也可以参照阅读材料的内容但不得直接

引用原文中的句子;

2. 文中不能出现真实姓名。

评分标准

概括准确. , 语言规范. , 内容合适. , 语篇连贯。

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