问题 多项选择题

关于UPS系统冗余2N或M(N+1)配置,以下说法正确的有()。

A.由两套或多套UPS系统串联组成的冗余系统

B.系统可用性较高,但设备利用率较低

C.在切换过程备机电流从零立即上升至负荷最大电流,对系统运行可靠性产生较大影响

D.造价较昂贵,有效减少UPS设备数量,降低UPS系统配置成本

答案

参考答案:B, D

阅读理解

Until late in the 20th century most Americans spent time with people of different generations. Now middle-aged Americans may not keep in touch with old people until they are old themselves.

That's because we group people by age. We put our three-year-olds together in day-care centers, our 13-year-olds in schools and sport activities, and our 80-year-olds in senior citizen homes. Why?

We live far away from the old for many reasons. Young people sometimes avoid the old to get rid of fears of aging and dying. It is much harder to watch someone we love disappear before our eyes. Sometimes it`s got hard that we stay away from the people who need us the most.

Fortunately, some of us have found our way to the old. And we have discovered that they often save the young.

A reporter moved her family into a block filled with old people. At first her children were disappointed. But the reporter baked banana bread for the neighbors and had her children deliver it and visit them. Soon the children had many new friends, with whom they shared food, stories and projects. "My children have never been lonely, "the reporter said.

The young, in turn, save the old. Once I was in a rest home (养老院)when a visitor showed up with a baby, she was immediately surrounded. People who hadn't gotten out of bed in a week suddenly were ringing for a wheelchair. Even those who had seemed asleep woke up to watch the child. Babies have an astonishing power to comfort and cure.

Grandparents are a special case. They give their grandchildren a feeling of security and continuity. As my husband put it "My grandparents gave me a deep sense that things would turn out right in the end." Grandchildren speak of attention they don't get from worried parents. "My parents were always telling me to hurry up, and my grandparents told me to slow down," one friend said. A teacher told me she can tell which pupils have relationships with grandparents: they are quieter, calmer and more trusting.

67. Now in an American family, people can find that___________.

A. children never live with their parents                            

B. not all working people live with their parents

C. aged people are supported by their grandchildren    

D. grandchildren are supported by their grandparents

68. Seeing a baby, the old people got excited because _______.

A. they had never seen a baby before                        B. the baby was clever and beautiful                   

C. the baby brought them the image of life              D. the baby's mother would take care of them           

69. Why are some children quieter, calmer and more trusting ?

A. Because they have relationships with their grandparents.                 

B. Because their worried parents ask them to act like that.

C . Because they have nothing to worry about.                                 

D. Because their teachers ask them to act like that.

70. Which of the following can show the fact that the old often save the young?

A. The old can become friends of the children and the children may not feel lonely.

B. The old get excited when they see a baby.

C. The old can cure the young when they are sick.

D. Babies have an astonishing power to comfort and cure.

BCAA

单项选择题