问题 选择题

下列说法中正确的是

A.变化的磁场周围一定产生变化的电场

B.在真空中,频率越高的电磁波传播速度越大

C.要提高LC 振荡电路辐射电磁波的本领,应该采取的措施之一是尽可能使电场和磁场分散开

D.当处于电谐振时,只有被接收的电磁波才能在接收电路中产生感应电流

答案

答案:C

均匀变化的磁场周围一定产生稳定的电场,在真空中电磁波传播速度总是等于光速C,当处于电谐振时,接受电磁波的LC震荡回路也会产生感应电流

阅读理解

第三部分:阅读理解(共20小题,每题2分,满分40分)

阅读下列短文,从每题所给的四个选项(A、B、C和D)中,选出最佳选项。

Sam, an unemployed piano tuner, said it was only the second thing he had ever won in his life.The first thing was an Afghan blanket at a church raffle(抽奖) when he was 25 years old.But this was much bigger: it was $120,000! He had won the Big Cube, a state lottery( * * ) game.To win, a contestant must first guess which number a spinning cube will stop on.The cube has six numbers on it: 1X, 10X, 50X, 100X, 500X, and 1000X.If he is correct, the contestant must then guess which of two selected variables(变量) is going to be greater.So, just guessing which number appears on the cube does not guarantee that you will win any money.

Sam correctly guessed 1000X, but he still had to choose between two variables.One variable was the number of cars that would run the stop sign at Hill Street and Lake Avenue in six hours.The other variable was the number of times that a teenage boy would change TV channels in a three-hour period.This was a tough decision.

Finally, Sam flipped a coin.It came up heads, so Sam picked the teenager.He picked right.The stop sign was run only 76 times, but the teen clicked 120 times.Sixty-year-old Sam jumped for joy, for he had just won 1000 times 120, or $120,000.Sam dreamily left the lottery studio.Talking excitedly on his cell phone while crossing the street, he got hit by a little sports car.

Sam is slowly getting better.He was in the hospital for a month.His hospital bill was $110,000.And the insurance company for the little sports car’s owner sued(起诉)Sam for $9,000 worth of repairs.Also, Sam still has to pay federal taxes on his winnings.Sam doesn’t play the state lottery any more.He says it’s better to be unlucky.

56.What can be inferred about Sam from the passage?

A.He always has bad luck.            B.He seldom goes to a raffle.

C.He is a very careful person in life.    D.He used to be crazy about lottery tickets.

57.Which of the following played a vital role in Sam’s winning the big prize?

A.The cube. B.The coin.  C.The blanket.     D.The stop sign.

58.Which of the following is TRUE according to the passage?

A.The lottery game was a complete lie.

B.Sam was quite familiar with the boy.

C.The owner of the car is now in hospital.

D.Sam will have none of the prize money left.

59.What could be the best title for the passage?

A.Curiosity killed the cat      B.Joy puts heart into a man

C.Extreme joy ends in sorrow    D.A bird in hand is worth two in the bush

单项选择题 A1/A2型题