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问题 多项选择题

当（）中任一条件满足时，机组的汽机跳闸连锁保护将动作停机。

A.DEH后备超速保护动作

B.DEH转速达107～111%额定转速

C.DEH系统电源故障

D.MFT动作

答案

参考答案：A, D

选择题

Wait a minute, __________?

A．shall you

B．will you

C．do you

D．don’t you
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单项选择题

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
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