Miss Evans taught physics in a London school. Last month she was explaining to her class a

Miss Evans taught physics in a London school. Last month she was explaining to her class about sound, and she decided to test them to see how successful she had been in her work. She said to them, Now, I have a sister in Washington. If I was calling her on the telephone, and at the same time you were 20 meters away and listened to me from the other side of the street, who could hear what I said earlier, my sister or you? And why?
The cleverest boy at once answered, “Your sister, Miss Evans, because electricity (电)travels faster than sound waves(波).” That’s very good, Miss Evans answered, but then one of the girls put up her hand, and Miss Evans said, Yes, Betty?
“I don’t think so. Betty said, Your sister would hear you earlier because when it’s eleven o’clock here, it’s only six o’clock in Washington.”
    6. Miss Evans was teaching her class     .
A. about sound                       B. to hear some strange sound
C. about electricity                    D. how to say time
    7. She wanted to make her students know    .
A. whether she could hear her sister in Washington
B. whether her students could hear her from 20 meters away
C. which was faster, London or Washington
D. electricity travels faster than sound waves
    8. The cleverest boy thought that    .
A. sound waves travel faster than electricity
B. they would hear her sister in Washington first
C. Miss Evans’s question wasn’t right
D. Miss Evans’s sister would hear her earlier
     9. Miss Evans    .
A. thought Betty’s answer was much better
B. thought the cleverest boy’s answer wasn’t so good
C. was satisfied with what the girl had said
D. was satisfied with(对...感到满意) what the cleverest boy had said
    10. Betty thought the cleverest boy was wrong, because    .
A. clocks in Washington showed a different time from those in London
B. electricity was slower than sound waves
C. they were only 20 meters away from the telephone
D. electricity travels as fast as sound wavesA