Section BDirections: In this section, you will hear 3 short passages. At the end of each p

Section B

Directions: In this section, you will hear 3 short passages. At the end of each passage, you will hear some questions. Both the passage and the questions will be spoken only once. After you hear a question, you must choose the best answer from the four choices marked A, B, C and D.

听力原文： Professor Wang is a physics teacher in Beijing. Once she was explaining to one of her classes about sound. She decided to test the students to see how well they had under- stood her. "I have an uncle in Xinjiang." she said. "Sup- pose I was calling him on the phone from here, and at the same time you were 25 metres away, listening to me. Who would hear me first, my uncle or you - and for what reason？" Ma Hue at once answered, "Your uncle, Professor Wang, because sound- waves travel slower than electricity.”

"Good," said the professor, but then another boy raised his hand.

"Yes, Li Ming？" said Professor Wang.

" Of course your uncle would hear you first," Li Ming said, "but that' s because of the time difference. When it ' s nine o' clock here, it' s seven o' clock in Xinjiang."

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A．By asking some students to explain the reason.

B．By giving them a test on the speed of sound.

C．By using a vivid question to check them.

D．By asking the students to restate his words.