题干

下列实验现象描述正确的是(   )

A:磷在空气中燃烧,产生大量的烟雾

B:电解水的实验中,负极产生的气体能使带火星的木条复燃

C:在CO还原氧化铜的实验中,固体的颜色由红色变黑色

D:铁在氧气中燃烧,火星四射,生成黑色的固体

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答案(点此获取答案解析)

D

同类题3

    Jim, a successful businessman, told the experience of his childhood.
    When he was 12, his parents 1. He was alone and didn’t get on well with others. People always laughed 2 him. No one showed kindness (友善) to him. His only friend was a dog named Tige.
    One day as he walked down the street, a young lady was walking in front of him. Suddenly one of her bags dropped from her arms. As she stopped3, she dropped other bags. He came to help her.“Thank you, dear! You are a nice little boy!”She said kindly, smiling.
A special feeling came to him. These were 4 kind words he had ever heard. He watched her 5she went far away, and he whistled(吹口哨)to his dog and went directly to the river nearby.
    “Thank you, dear! You are a nice little boy!”he repeated the woman's words. Then in a low    6 he said to his dog,“You are a nice little dog!”Tige raised 7 ears as if(似乎)it understood.
    “Uh! Even a dog likes it!”he said,“Well, Tige, I won't say unkind words to you any more.”Tige waved its tail happily.
    The boy thought and thought. Finally he looked at himself in the river. He saw 8 but a dirty boy. He washed his face9. Again he looked. He saw a clean nice boy. He was amazed (震惊). From then on, he had a new life.
    After telling this, the businessman stopped for a while, and then he said,“Ladies and gentlemen, this is the very place where that kind woman planted in me the first seed (种子) of kindness. All of us should learn about kindness. 10a great power it has!” If you show kindness to others, you will be an able man.