离子交换器树脂被油污染有何危害？一旦被污染后如何处理？模拟操作过程？

气相色谱法测定水中挥发性卤代烃时，实验用水需经检验证明其中不含有挥发性卤代烃。

《变色龙》中作者塑造奥楚蔑洛夫这个人物典型的社会意义是 [ ]

A．揭露走狗奴才的丑恶灵魂。  

B．抨击腐败无能的沙皇统治。   

C．说明变色龙善于根据环境情况迅速变色以求得自身隐蔽的特征。   

D．揭露沙皇统治的黑暗，影射沙皇专制的虚伪和专横。

下列哪项不符合风筝的文化寓意（）

A.长寿

B.吉祥

C.求福

D.灾难

论侦查破案过程中利用情报的主要方式。

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.

It can be deduced from this passage that one should________.

A．learn new skills

B．be open-minded

C．have a good personality

D．keep pace with the times