问题 选择题
如图所示,理想变压器原、副线圈的匝数比为10:1,b是原线圈的中心接头,电压表V和电流表A均为理想电表.从某时刻开始在原线圈c、d两端加上交变电压,其瞬时值表达式为u=220sin100πt(V).下列说法正确的是(  )

A.当单刀双掷开关与a连接时,电压表的示数为22V

B.当单刀双掷开关与b连接时,电压表的示数为11V

C.当单刀双掷开关与a连接,滑动变阻器触头P向上移动的过程中,电压表的示数不变,电流表的示数变大

D.单刀掷开关由a扳向b时(滑动变阻器触头P不动),电压表和电流表的示数均变大

答案

答案:D

单项选择题
阅读理解

New York State has passed the USA’s first state law banning motorists talking on hand-held cell phones. The ban will begin November 1, although drivers caught using hand-held cell phones will be given only warnings during the first month.

First-time violators(违法者) will face a $100 fine. A second time call for a $200 fine and every violation after that will cost$500.

At least a dozen localities(地方) have established bans, starting in 1999; and 40 states have had bans proposed but not passed.At least 23 countries, including the Great Britain, Italy, Israel and Japan, ban drivers from using hand-held cell phones.

There are about 115 million cell phones in use in the United States and more than 6 million in New York State.

“To think that I’m not going to use cell phone when at the same time I can still use my laptop, I still can read a paper, I can still change my pants(裤子) while driving 65 mph. I think there’s just something wrong,” an official said.

Other critics noted that other things like eating, drinking coffee and applying make-up while driving posed(造成) at least as much of a concern. They suggested that the ban include a broader range of things.

1.How much fine will a hand-held cell phone user receive if he has been caught using it four times while driving after November?

A.$500.     B.$1000.   C.$1200.   D.$1300.

2.We can see from this passage that _______. 

A.the ban has been put into effect in most states in the U. S.

B.many of the developed countries forbid drivers using hand-held cell phones

C.over fifty localities or states ban drivers from using hand-held cell phones

D.more people in the U. S. are against the ban than for it

3.The official mentioned in this passage _______. 

A.does not agree with this ban

B.doesn’t believe using hand-held cell phones while driving will cause any danger

C.doesn’t understand why hand-held cell phones alone should be banned among many others

D.believes changing pants while driving will cause greater danger

4.The writer intends to tell us in the last paragraph that _______.

A.it is not fair to have this ban passed

B.the ban will never be passed in the whole country

C.more activities of the same kind should also be banned

D.the ban will meet with more criticism

5.This article is most probably taken from _______.

A.a newspaper article            B.an advertisement

C.a personal diary                    D.a letter