选择重物起吊点的位置应根据哪些原则进行？
参考答案：
应根据下列原则进行：
（1）有吊环的物体，吊点要用原设计的吊耳。
（2）如果没有规定的吊点，可在物件两端的四点上绑扎，然后根据具体情况选择吊点，应使吊点与重心在一条直线上；
（3）如平吊长形物体，吊点一般在重心两端，吊钩通过重心，如竖吊物件，则吊点应在重心之上。
（4）吊方形物件时，四根绳索的位置在重心四边；
（5）拖拉长物件时顺长度方向拖拉时，绑扎点应在重心点的两端，横拉时，四根绳索的两个绑扎点应在重心等距离的两端。
| 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 the first paragraph, which of the following is true
A．People don’t have to gain education.
B．People don’t have to learn job skills.
C．People don’t have to be treated as equals.
D．People don’t have chances to begin anew.