已知某用户配电变压器视在功率为SN(kVA),短路损耗PK,短路无功损耗QK。平均功

题型:单项选择题 案例分析题

问题:

已知某用户配电变压器视在功率为SN(kVA),短路损耗PK,短路无功损耗QK。平均功率Pav,轻载有功功率Pmin,总平均功率因数cosφ1,轻载功率因数cosφ2,现对变压器低压侧进行无功补偿,补偿后平均功率因数达到cosφ3~cosφ4

计算轻载时固定补偿容量Qg应使用公式()。

A.

B.

C.

D.

考点:国家电网农网配电生产技能考试避雷器、电力电容器、接地装置避雷器、电力电容器、接地装置题库
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IP 服务的3个主要特点是

A. 不可靠、面向五连接和尽最大努力投递

B. 可靠、面向连接和尽最大努力投递

C. 不可靠、面向连接和全双工

D. 可靠、面向五连接和全双工

题型:单项选择题 案例分析题

Homework can put you in a bad mood (心情), and that might actually be a good thing. Researchers from the University of Plymouth in England doubted whether mood might affect the way kids learn. To find out the answer, they did two experiments with children.

The first experiment tested 30 kids. Some shapes (图片) were hidden inside a different, larger picture. The kids had to find the small shapes while sitting in a room with either cheerful or sad music playing in the background. To test their mood, the scientists asked the kids to point to one of five faces, from happy to sad. Children who listened to cheerful music tended to point to the smiley faces while the others pointed to the unhappy ones. The researchers found that sad kids took at least a second less to find the small shapes. They also found an average of three or four more shapes.

In the second experiment, 61 children watched one of two scenes from a film. One scene was happy, and the other was sad. Just like in the first experiment, kids who saw the sad scene acted better compared to the others.

The researchers guessed that feeling down makes people more likely to focus on a problem or difficult situation. Not all scientists agree with them, however. Other studies argued that maybe, that cheerful music in the first experiment distracted (使分心) kids from finding shapes.

While scientists work on finding out the answers, it still might be wise to choose when to do your tasks according to your mood. After eating a delicious ice cream, for example, write an essay.

小题1:Researchers did experiments on kids in order to find out ______.

A.how they really feel when they are learning

B.whether mood affects their learning ability

C.what methods are easy for kids to learn

D.the relationship between sadness and happiness小题2:The researchers found in the first experiment that ______.

A.kids who listened to happy music turned out to be energetic

B.kids who listened to sad music liked to choose smiley faces

C.kids worked harder in the background of happy music

D.sad music helped kids find out small shapes quickly小题3:What can we learn from the text?

A.The researchers will continue to do experiments.

B.The researchers have found a clear answer.

C.The experiments are popular among kids.

D.Kids change their feelings more easily.小题4:We can infer that the text is ______.   

A.a science survey

B.a research report

C.a school project

D.an introduction to an experiment

题型:单项选择题 案例分析题
船从河里航行到大海中继续行驶时,下列说法正确的是(   )

A.海水对船的浮力大,船将浮起一些

B.海水比河水深,船将沉下一些

C.船受的浮力不变,但船将浮起一些

D.船受的浮力不变,船的高低保持不变

题型:单项选择题 案例分析题

BSP方法实现的主要步骤是定义企业目标、定义企业过程、定义______、最后定义信息系统总体结构。

题型:单项选择题 案例分析题

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