问题 选择题

下列有关声现象的说法中,正确的是(  )

A.气体不能发声

B.声音是一种波

C.声音能在真空中传播

D.声源的振幅越大,音调越高

答案

A、因为气体、液体和固体都是物质,所以气体能够发声,故A选项错误;

B、声音是以声波的形式向外传播的,因此B选项正确;

C、声音不能在真空中传播,故C选项错误;

D、因为发声体的频率越高,音调越高,而振幅决定声音的响度,所以D选项错误.

故选B

阅读理解

C

Bob, a student who does computer studies at Texas University, found his own parents with the help of Internet. The news got around soon and many of his friends came to share his happiness. Some of them even asked him to help them find jobs on the Internet.

Before he turned to Internet for help, Bob had spent one year looking for his parents who left him 26 years ago when he was a baby. Using knowledge on computer and network, Bob found out his birth information and sent a notice to Internet in hope of finding his parents. Only one day later, Bob’s dream came true.

When Bob flew to Los Angles to meet his father, Stephen, they embraced(拥抱) each other lovingly and warmly. They enjoyed the family meeting. Later on Mother’s Day, Bob met his mother Silva.

Three years ago, Stephen himself also tried hard to look for his son but his hard try ended in nothing. Bob’s try on the Internet has turned to be a happy ending.

54. Which of the following is unknown to us ?

A. Bob’s birth information               B. Where Bob’s father lives        

C. Why Bob’s parents left him                    D. What Bob does

55. Bob couldn’t find his parents a year ago because______.

A. his parents didn’t want to see him       B. he couldn’t get useful information 

C. he didn’t want to                            D. he was just a student

56. Before he found his parents, Bob had to ______.

A. made a lot of friends                  B. fly to Los Angles          

C. sent a notice to Internet every day           D. find out his own birth information

57. How long did it take Bob to find his parents after using the Internet?

A. Only one day       B. About one year         C. 3 years                     D. 26 years

判断题