劳务分包单位应开展安全教育培训，应提前将参与施工的所有人员培训考核情况书面提交承包单

Modern industrial society grants little status to old people. In fact, such a society has a system of built-in obsolescence. There is no formal system for continuing our education throughout our life in order to keep up with rapidly changing knowledge. When our education and job skills have grown obsolete, we are treated exactly like those who have never gained an education or job skills and are not encouraged or given the opportunity to begin anew.
As a society becomes more highly developed, the overall status of older people diminishes. Improved health technology creates a large pool of old people, who compete for jobs with the young. However, economic technology lowers the demand for workers and creates new jobs for which the skills of the aged are obsolete, forcing older people into retirement. At the same time, young people are being educated in the new technology and are keeping pace with rapid changes in knowledge. Finally, urbanization creates age-segregated neighborhoods. Because the old live on fixed incomes, they must often live in inferior housing. All these factors—retirement, obsolete knowledge and skills, inferior standards of living—lower the status of the aged in society.
A century ago, when one could expect to live only to 50 or so, the life span more or less coincided with the occupation and family cycle. But today the average life span allows for fifteen to twenty years of life after these cycles. It appears that our life span is outpacing our usefulness in society.

According to this passage, the status of the aged is lowered by their ______.

A．forced retirement

B．inferior housing

C．longer life span

D．fixed incomes

假如你是王杰，现在银川姨妈家探亲。到达银川一周后，你用英语给父母发封电子邮件，内容要点如下：

1.于上周六早晨抵达银川，旅途愉快；  2.姨妈全家人身体都好，他们都对我非常亲切；

3.这几天表兄们带我参观了博物馆、影视城 (the Western Film City) 等； 

4.假如明天天气好，我们打算去沙湖......；  5.谈谈你对银川的印象。（至少写出3点）

要求：邮件须包括所有内容要点，要求语句通顺、意思连贯。80词左右。

Dear Dad and Mom,

______________________________________________________________________________

______________________________________________________________________________

____________________________________________________________________________________________________________________________________________________________

______________________________________________________________________________

Uncle and Aunt send their best wishes.

Love,

Wang Jie

作为石油的伴侣，天然气的生成条件要比石油更为多样化，石油要达到一定的埋藏深度才能大量生成，而天然气则从浅到深都可，浅的也许只有几百米，深的则有上万米。就物质来源说，石油以水中浮游的动植物有机质为主，而天然气还可以有高等植物等有机质。对于成因，目前地质科学界绝大多数的转接都赞成有机说，认为石油和天然气就是由远古时代死去的各种生物体转化而成。 不能从这段文字中得知的是：

A.石油比天然气埋藏深 

B.石油大多由水生生物转化而成 

C.石油和天然气都是由各种生物体转化的 

D.水中浮游的动植物有机质也是天然气的

何谓中和抗体?

如图4-2-14所示，在铅直面内的一块圆板上刻有三道直槽AO、BO、CO，三个质量相等的小球M₁、M₂、M₃在重力作用下自静止开始分别沿各槽运动，不计摩擦，则（）到达O点。

A．M₁小球先

B．M₂小球先

C．M₃小球先

D．三球同时