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问题 选择题

如图所示，无限大磁场的方向垂直于纸面向里，A图中线圈在纸面内由小变大（由图中实线矩形变成虚线矩形），B图中线圈

正绕a点在平面内旋转，C图与D图中线圈正绕OO′轴转动，则线圈中不能产生感应电流的是（　　）

A．

B．

C．

D．

答案

A、线圈在纸面内由小变大，磁通量增大，会产生感应电流，故A错误．

B、线圈正绕a点在平面内旋转，磁通量都不变化，因此不会产生感应电流，故B正确．

C、C图与D图中线圈正绕OO′轴转动，磁通量都在减小，会产生感应电流，故C、D错误．

故选B．

问答题 简答题

举例说明“present-in-hand”（应手之物）与“ready-to-hand”（现成在手之物）。
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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 2: ______
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