试题与答案

某企业电网先期装有4台发电机(2×30MW+2×42MW),后期扩建2台300MW机

题型:单项选择题

题目:

某企业电网先期装有4台发电机(2×30MW+2×42MW),后期扩建2台300MW机组,通过2回35kV线路与主网相联,主设备参数如表所列,该企业电网的电气主接线如图所示。

5号、6号发电机采用发电机变压器组接入330kV配电装置,主变压器参数为360MVA,330/20kV,Ud=16%。当330kV母线发生三相短路时,计算由一台300MW机组提供的短路电流周期分量起始值最接近下列哪项数值?() A.1.67kA B.1.82kA C.2.00kA D.3.54kA

A.1.67kA

B.1.82kA

C.2.00kA

D.3.54kA

答案:

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题型:阅读理解

阅读理解。

   Department stores sell ready-to-wear clothing, which is also called ready-made clothing.

Such clothing is made in fixed sizes. Those people who find that ready-made clothing fits

them well can save money by buying it. Most often, People do not fit exactly into a producer's

size. Their clothing must be changed to make it fit better. However, most changes are not

very expensive. The small cost of most changes means that ready-made clothing can meet the

needs of most customers. 

   Those who can afford it often get someone to design (设计) and make their clothing. Such

clothing is called custom-made. The person who makes it measures (测量) the customer, and

then sews it so that it fits perfectly. Changes are not needed. Custom-made clothing is largely

sewn by hand, has better quality, better material, and is of the style you have chosen. Of course,

it costs much more than ready-to-wear clothing. You need to pay the difference for the special

fitting and better skill that you are receiving. This often means that you spend double or mor

than you would for a ready-made garment.

   Custom-made clothing is not always that much better than ready-made clothing. It costs more

partly because only one garment has been made, just for you. Companies that produce ready-made

products make thousands of garments at a time. This means they can buy large amounts of material.

Workers cut each size by the hundreds. Companies work out ways to make the garments, quickly

by machine and pay workers according to their skill. Thus they can sell the finished products at a

low price while still making money. Most of the clothing sold in the United States is made in this way.

Customers gain from the lower prices which are made possible by mass production. It may or may

not give them high quality.

1. According to the passage, people who buy ready-made clothing _____. [ ]

A. wish to make changes

B. can fit into the sizes

C. want to make it better

D. will spend less money

2. We can learn from the passage that custom-made clothing is _____. [ ]

A. specially made

B. fashionably designed

C. chosen by few people

D. made with difficulties

3. Which of the following is true about ready-made clothing? [ ]

A. It is of poor quality.

B. It suits all people.

C. It takes more time to make it.

D. It is time-saving to make it.

4. The purpose of the writer is _____. [ ]

A. to explain why custom-made clothing costs more

B. to show the advantages of mass production

C. to provide information about different kinds of clothing

D. to tell readers how to make money from ready-made clothing

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