问题
选择题
氧化还原反应的实质是（ ）
A．元素化合价发生变化
B．反应中有氧原子的得失
C．反应中有电子得失或电子对的偏移
D．反应后生成新物质
答案
答案：C
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氧化还原反应的实质是（ ）
A．元素化合价发生变化
B．反应中有氧原子的得失
C．反应中有电子得失或电子对的偏移
D．反应后生成新物质
答案：C
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| When Alice started to cycle home from Jenny's house, she wasn't nervous. She was certainly not afraid of the dark. 1 , it was only a 15-minute ride home. But halfway there, she began to wish that she hadn't been so 2 . As she rounded a sharp bend, it suddenly 3 cold-very cold. Alice's breath became puffs of white cloud and her legs were so cold that it became hard to ride. With her heart beating fast, she struggled so hard to move 4 that she didn't hear the car which suddenly appeared beside her. She stopped by the road. The big black car also 5 . Slowly, the passenger-window began to slide down. Alice held her breath. In the soft light inside the car, something 6 . Then, the light brightened and Alice was staring at a sweet, grey-haired old lady. "Hello, dear," said the old lady. "I need 7 . I'm afraid I'm lost. I need to find the nearest airport. I must be there in the next five minutes." "Airport? You 8 are lost," Alice said. "You need to go back five kilometers 9 you reach the T-junction. Turn left and 10 for about another 10 kilometers to the main highway. From there, just follow the 11 to the airport. But I'm afraid there's no 12 you'll get there in five minutes!" "Thank you very much, dear," replied the old lady. "Don't worry-I'll 13 in time." The 14 moved up and the car started off. A little way ahead, it 15 and with headlights flashing, it drove past Alice. But then, something 16 happened. The car began changing. First, its color 17 from black to silvery-grey. Then, the wheels began disappearing, but the car continued to move forward, 18 just above the ground. As the car 19 into the dark sky, the big red tail-lights grew larger and larger and glowed more and more brightly. With a faint whistling 20 , the car was gone in seconds, leaving Alice shaking her head in disbelief… | ||||
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