You can connect a wire to the positive and negative ends of a battery __________.

A．to develop a maglev train rail system

B．to explain why maglev trains are faster

C．to pull and push the train forward

D．to create a magnetic field

E．to experiment with the maglev train

F．to travel from Paris to Rome in about two hours

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参考答案

答案解析

第二段说，把电线与干电池相连接就能产生一个小磁场，而磁浮列车的运动原理与此相同。第二段第三句“You can easily creme a small electromagnet yourself by connecting the ends of a copper wire to the positive and negative ends of an AA-cell battery．”是选择D的依据。

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1 A unique system of magnetic fields is created by the coils __________.

A．to develop a maglev train rail system

B．to explain why maglev trains are faster

C．to pull and push the train forward

D．to create a magnetic field

E．to experiment with the maglev train

F．to travel from Paris to Rome in about two hours

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2 The frictionless maglev train enables you __________.

A．to develop a maglev train rail system

B．to explain why maglev trains are faster

C．to pull and push the train forward

D．to create a magnetic field

E．to experiment with the maglev train

F．to travel from Paris to Rome in about two hours

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3 请根据短文的内容，回答题。

Good Table Manners

Manners play an important part in making a favorable impression at the dinner table. Here are some general rules:
Napkin (餐巾 ) use:
The meal begins when the host unfolds his or her napkin. This is your signal to do the same,so place your napkin on your lap. Unfold it completely if it is a small napkin, or in half, lengthwise( 纵向地) , if it is a large dinner napkin.
If you need to leave the table during the meal, place your napkin on your chair as a signal to your server that you will be returning. Once the meal is over, place your napkin neatly on the table to the right of your dinner plate. Do not refold it.
Use a napkin only for your mouth. Never use it for your nose, face or forehead.
Use of utensils ( 餐具):
Start with the knife, fork or spoon furthest from your plate, and work your way in, using one utensil for each course.
If soup is served, remember to spoon away from yourself. This helps stop the drips. Do not put the entire soup spoon in your mouth. Instead, fill a soup spoon about 75 per cent with soup, and sip(啜饮) it from the side noiselessly.
After finishing dinner, place the knife and fork parallel to one another across the plate with the knife blade facing inward toward the plate.
Using your fingers:
Here's a list of finger foods: sandwiches, cookies, small fruits or berries with stems, French fires and potato chips, and hamburgers.
Chew (咀嚼) with your mouth closed and don't make noise: don't talk with your mouth full.
Bread must be broken with your hands. It is never cut with a knife.
Don't pick something out of your teeth. Instead, excuse yourself to the bathroom.
If possible, try not to cough at the table.
Do not put your elbows (肘) on the table. In France, it is essential to have both hands above the table at the same time.
Do not put bones or anything else on the table. Things that are not eaten should be put on your plate.
Where is the napkin normally placed during the meal?

A．On your chair.

B．On the table.

C．On your lap.

D．On your plate.

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