题干

《美国化学会志》报道,中国科学家以二氧化碳为碳源,金属钠为还原剂,在470℃、80MPa下合成出金刚石,具有深远意义。下列说法不正确的是(     )       

A:由二氧化碳合成金刚石是化学变化

B:金刚石是碳的一种同位素

C:钠被氧化最终生成碳酸钠

D:金刚石中只含有非极性共价键

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B

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    Time is very important in our life. However, I had never realized it until I received a beautiful gold watch from my father one day when I was 19 years old. This watch always 1 me the importance of time in my life.
   It was a cold rainy day. My father asked me to go to the 2to pick up my uncle and take him home. I should have arrived there before 4:30p.m. We had a basketball match at school that afternoon and the match was so 3that I forgot the time. When the match was nearly over, I suddenly remembered my uncle and hurried to the airport .It was too late. He had left the airport and take a taxi to our house.
   I was very worried that my father would complain 4the thing. As soon as I entered the living room, I saw my uncle in the sofa looking very tired. I do not 5uncle and my father .I said hello to them in a very low voice .My father didn’t say 6.Instead, he asked me to sit7 him. “Peter, did you have a good time today?” I felt so sorry and answered in a 8 voice. “Yes, Dad, but I ’m really sorry .This will9happen again. I promise.”My father handed me a box with a beautiful gold watch inside .It was a gift my uncle bought for him. He gave it to me and said, “I hope you have learned something important today, and this watch will help you remember the importance of time.”
   The watch has been with me for twelve years .I wear it not because of its price, but because of 10I learned. It tells me to respect(重视)and never be late to do what I have promised to .