问题 选择题

下列方法中可增强电磁铁磁性的是(  )

A.增大螺线管中的电流

B.减小螺线管的线圈匝数

C.增加电磁铁的通电时间

D.改变螺线管中的电流方向

答案

A、匝数相同时,增大线圈中的电流,电磁铁的磁性增强.故A说法正确.

B、线圈中的电流相同时,减小线圈匝数,电磁铁的磁性减弱.故B说法不正确.

C、电磁铁通电时间的长短,与电磁铁磁性的强弱没有必然的联系.故C说法不正确.

D、改变电流的方向,只能改变通电螺线管的磁极.故D说法不正确.

故选A.

阅读理解

阅读理解

         There is a one-day holiday in most countries on New Year's Eve. There are several interesting customs in the West, and there are many differences from country to country.  

         Though Christmas is a family get-together. New Year for some is a time to be with friends too. Parties are most often held to welcome New Year. At such arties, there is food and drink and dancing until the time nears for the coming of New Year.  

         At midnight, people often say “Happy New Year ”to each other. Champagne(香槟酒)is a favorite drink for New Year. In many western countries fireworks(烟火)are let off at midnight ,and many people like to make a noise, possibly to drive away bad spirits(幽灵).  

        One important song is often sung at New year-the Scottish(苏格兰)song of Auld Lang syne (good times long ago.)

1. People usually have great celebrations for New Year on         .   

A. New Year's Day                    

B. the night before New Year's Eve  

C. the night of New Year's Day      

D. the night before New Year's Day

2. In the West, New Year is also a time when.         .   

A. friends get together              

B. friends write to each other  

C. people can have a week's holiday  

D. people came from country to country

3. The word “customs ”in the passage means          .   

A. 习俗                    

B.  聚会            

C. 饮食                  

D. 活动

4.At midnight on New Year's Eve western people often          .  

① hold parties to welcome New Year        

② make a noise to drive away bad spirits  

③ drink with friends or families          

④ say “Happy New Year ”to each other  

⑤ sing an important French song          

⑥ let off fireworks  

A. ①②③④             B. ③④⑤⑥           C. ②③④⑥         D. ①②⑤⑥        

5. This passage mainly talks about

A. western people drink together on New Year's Eve  

B. what western people do on New Year's Day  

C. how western people spend their New Year's Eve

D. western people have a good time on New Year's Day

填空题