题干

装满氧气的集气瓶,按右图所示,用带火星的木条分别以甲、乙两种方式迅速插入,发现木条复燃,且在甲中燃烧比在乙更旺。上述实验说明了氧气具有的性质是:


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氧气具有助燃性,氧气密度比空气略大

同类题5

    When I was growing up in America, I was ashamed of my mother's Chinese English. Because of her English, she was often treated unfairly. People in department stores, at banks, and at restaurants did not take her seriously, pretended(假装) not to understand her, or even acted as if they did not hear her.
    My mother has realized the disadvantages of her English as well. When I was fifteen, she used to have me call people on phone to pretend I was she. I was forced to ask for information or even to yell at people who had been rude to her. One time I had to call her stockbroker(股票经纪人). I said in a voice that was not very convincing, “This is Mrs. Tan.” And my mother was standing beside me, whispering loudly, “Why he doesn't send me the check. It's already two weeks late.”
    And then, in perfect English I said: “I'm getting rather anxious .You agreed to send the check two weeks ago, but it hasn’t arrived.” Then she talked more loudly. “What does he want? I’ll come to New York and say it in front of his boss.” And so I turned to the stockbroker again, “I can't accept any more excuses. If I don’t receive the check immediately, I have to speak to your manager when I am in New York next week.”
    The next week we ended up in New York. While I was sitting there red-faced, my mother, the real Mrs. Tan, was shouting to his boss in her broken English. When I was a teenager, my mother’s broken English embarrassed (使困窘) me. But now, I see it differently. To me, my mother’s English is perfectly clear, perfectly natural. It is my mother tongue. Her language, as I hear it, is clear and direct. It was the language that helped me form the way I saw things, expressed ideas, and made sense of the world.