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如图所示，L1、L2是高压输电线，图中两电表示数分别是220V和10A，已知甲图中原 副线圈匝数比为 100：1，乙图中原副线圈匝数比为1：10，则（　　）

A．甲图中的电表是电压表，输电电压为22000V

B．甲图是电流互感器．输电电流是100A

C．乙图中的电表是电压表，输电电压为22000V

D．乙图是电流互感器，输电电流是100A

答案

A、根据变压器电压表等于匝数比

U1
U2
=
n1
n2
，有U1=
n1
n2
U2=
100
1
×220V=22000V，故A正确．

B、甲图是电压互感器．故B错．

C、乙图是电流互感器，电表是电流表．故C错．

D、只有一个副线圈的变压器，电流比等于匝数的反比

I1
I2
=
n2
n1
，有I1=
n2
n1
I2=
10
1
×10A=100A，故D正确．

故选AD．

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Part 2


Questions 9-18


·Read the following passage and answer questions 9-18.
1. When one of your car tires goes flat, there are two things you can do. Groan and change or, if you don’t have a spare, stand helplessly behind the road and hope someone to your rescue. Now comes a third alternative, called Quickwheel. It is designed to get disabled motorists rolling again as quickly as possible.
2. Quickwheel is essentially a tiny trailer — complete with three tough little wheels of it’s own — that support the flat tire and enable the motorist to drive to the service station without losing much time or expending much energy. The product is manufactured in the Netherlands but is owned and marketed by a US company. Quickwheel inc. of Greenwich, Connecticut. According to the firm’s president, Robert Bockweg, the product meets each of the major concerns that consumers associate with flat tires: safety lost time and physical exertion.
3. To use it, motorists simply unfold the product to its fully extended position, set it in front of the disabled tire, drive the car on to the Quickwheel’s ramp and attach a special safety strap over the tire. The tire is then locked, or cradled, in Quickwheel’s metal frame. The device’s three wheels do the rest of work.
4. According to Quckwheel Inc., its product can be driven "four miles" at speeds of up to 45 miles per hour without any noticeable change in the vehicle’s breaking or steer operation. The company also claims that it can be used on just any type of car, jeep, mini-van or trailer.
5. Bockweg says that Quickwheel will be sold in the US, at a price of $150. Distribution agreements now being negotiated should make the product available in Japan, Canada and West Europe in the future.

Questions 9-13


·For questions 9-13, choose the best title for each paragraph from below.
·For each numberedparagraph (1-5), mark one letter (A-G) on the Answer Sheet.
·Do not mark any letter twice.
  • A. The future marketing of Quickwheel.
  • B. The advantages of the Quickwheel.
  • C. How does Quickwheel work
  • D. The ways of dealing with flat tires.
  • E. Quickwheel can get disabled motorists rolling again.
  • F. An introduction of Quickwheel.
  • G. Why is the Quickwheel invented

Paragraph 1: ______
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棉花对氮（）钾肥料需要最多的时期为（）。
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