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在物理学中,磁场的强弱用磁感应强度(用字母B表示,国际单位是特斯拉,符号是T)来表示,磁感线越密的地方,磁场越强,磁感应强度B越大.

(1)在图20中,甲为某磁极附近磁感线的方向和分布的示意图,由图可知,该磁极为 ▲ 极,若在l处放置一个小磁针,当小磁针静止时,其指向应是图乙中的  ▲   .
(2)磁敏电阻阻值的大小随磁场的强弱变化而变,图丁是某磁敏电阻R的阻值随磁感应强度B变化的图象,据图线可知,磁敏电阻的阻值随磁感应强度B的增大而▲ .图线没有过坐标原点,说明  ▲  .
(3)王强设计了一个可以测量该磁敏电阻R的电路如图丙所示,(其中磁敏电阻所处的磁场未画出).将该磁敏电阻R放置在磁场中的位置某处,测出电阻后,利用R—B特性曲线可以读出相应的磁感应强度.
①在图甲磁场中1处,测得的数据如图20表中所示,则该磁敏电阻的测量值为 ▲ Ω. 
②根据该磁敏电阻的R-B特性曲线可知,1处的磁感应强度为   ▲    T.
③在实验过程中,仅将磁敏电阻从1处移至2处,其它条件不变,那么电流表的示数
▲   (填“增大”、“减小”或“不变”).
④依据上述方法获得的磁感应强度B的测量值与该点实际值存在不小的误差,为尽可能准确反映空间某点磁场的强弱,你认为在选择磁敏电阻时应注意什么问题?

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在物理学发展的过程中,许多物理学家的科学发现推动了人类历史的进步。以下叙述中,正确的说法是
A.哥白尼创立地心说
B.相对论的创立表明经典物理学已不再适用
C.卡文迪许建立了行星运动定律
D.牛顿总结出牛顿运动定律和万有引力定律,建立完整的经典力学体系

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阅读理解(共5小题,每小题2分)
Tom saw an advertisement(广告)in a newspaper for a beautiful bicycle. It cost 55 pounds so he went to the shop and asked to see one of the wonderful bicycles. The owner of the shop was happy to show one to Tom. Tom examined it carefully and then turned to the owner and said, ‘There isn’t a lamp(灯)on this bicycle, but there was one on the bicycle in your advertisement.” “Yes, sir” answered the man, “but the lamp isn’t included(包括)in the price of the bicycle.” “Not included in the price of the bicycle?” Tom said angrily, “But that’s not honest. If the lamp is in the advertisement, it should be included in the price.” “Well, sir” answered the shop owner coldly. “There is also a girl on the bicycle in the advertisement, but we can not give you a girl with the bicycle, either.”
【小题1】In the advertisement, there was a     and a  on the bicycle.
A. lamp, girl         B. newspaper, shop owner        C. lamp, man
【小题2】After he read the advertisement. Tom decided to    .
A.see and buy the lamp    B. ask the owner   C. see and buy the bike 
【小题3】Tom  after he looked at the bike carefully
A. returned the bike to the shop owner
B. didn’t find a lamp on the bicycle
C. showed the bike to the shop owner
【小题4】Tom thought it was  for the shop owner to sell the bike without a lamp while there was one in the advertisement.
A. wrong    B. honest    C. necessary
【小题5】The text gives us a lesson that   .
A. we must read a newspaper carefully
B. bicycle must be examined carefully before they are bought
C. sometimes we can’t completely(完全地)believe an  advertisement

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阅读理解(共5小题,每小题2分)

Tom saw an advertisement(广告)in a newspaper for a beautiful bicycle. It cost 55 pounds so he went to the shop and asked to see one of the wonderful bicycles. The owner of the shop was happy to show one to Tom. Tom examined it carefully and then turned to the owner and said, ‘There isn’t a lamp(灯)on this bicycle, but there was one on the bicycle in your advertisement.” “Yes, sir” answered the man, “but the lamp isn’t included(包括)in the price of the bicycle.” “Not included in the price of the bicycle?” Tom said angrily, “But that’s not honest. If the lamp is in the advertisement, it should be included in the price.” “Well, sir” answered the shop owner coldly. “There is also a girl on the bicycle in the advertisement, but we can not give you a girl with the bicycle, either.”

1.In the advertisement, there was a     and a  on the bicycle.

A. lamp, girl         B. newspaper, shop owner        C. lamp, man

2.After he read the advertisement. Tom decided to    .

A.see and buy the lamp    B. ask the owner   C. see and buy the bike 

3.Tom  after he looked at the bike carefully

A. returned the bike to the shop owner

B. didn’t find a lamp on the bicycle

C. showed the bike to the shop owner

4.Tom thought it was  for the shop owner to sell the bike without a lamp while there was one in the advertisement.

A. wrong    B. honest    C. necessary

5.The text gives us a lesson that   .

A. we must read a newspaper carefully

B. bicycle must be examined carefully before they are bought

C. sometimes we can’t completely(完全地)believe an  advertisement

 

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阅读理解

One day a poor farmer was taking a bag of rice to town. Suddenly the bag fell from his horse on the road. He didn’t know what to do about it because it was too heavy for him to lift (举起) by himself. He only hoped that somebody would soon pass (经过) by and help him.

Just at this moment a man riding a horse came up to him. But the farmer was very disappointed(失望的)when he saw who he was. It was the great man living nearby. The farmer had hoped to ask another farmer or a poor man like him for help.

But to his surprise, the great man got off his horse as soon as he came nearer. He said to the farmer, “I see you need help, friend. How good it is that I’m here just at the right time,” Then he took one end of the bag, the farmer took the other. They together lifted and put it on the horse.

“Sir,” asked the farmer, “how can I pay you?”

“It’s quite easy,” the great man answered with a smile, “Wherever (无论在哪里) you see anyone in trouble, do the same for him.”

1.What happened when the farmer went to town?

A.His horse’s leg was hurt.

B.The bag fell from his horse.

C.The farmer lost his bag.

D.His bag was stolen.

2.The farmer didn’t lift the bag onto the horse by himself because      .

A.the bag was broken

B.the horse went away

C.the bag was too heavy

D.the farmer was ill

3. Why was the farmer very disappointed when he saw the great man? Because he thought the great man        .

A. couldn’t see him           B. could take away his bag

C. could take away his horse    C. couldn’t help him

4.Who helped the farmer?

A.A great man.

B.Another farmer.

C.A poor man.

D.A friend.

5.What does the story mainly (主要地) tell us?

A.Everybody should become a great man.

B.We should help the man who is in trouble.

C.Everybody couldn’t do as the farmer did.

D.We should pay for other’s help.

 

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