题干

分类和类比是学习化学的常用方法.

燃烧是人类最早利用的化学反应之一,火善用之为福,不善用之为祸.下面是一些常用的灭火方法:

①房屋着火时,用髙压水枪灭火;②森林着火时,将大火蔓延线路前的一片树木砍掉;③油锅着火时,用锅盖盖灭;④熄灭酒精灯时,用灯帽盖灭;⑤熄灭燃气灶火焰时,关闭阀门;⑥木材着火时,用水基型灭火器灭火;

请你从灭火原理角度,选择一种分类标准进行分类:

分类标准____ ,包括事例____  (填序号).

上一题 下一题 0.0难度 选择题 更新时间:2019-03-01 02:24:23

答案(点此获取答案解析)

隔绝氧气(或清除可燃物或降低可燃物的温度),③④(或②⑤或①⑥)

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    I was never very neat, while my roommate Kate was extremely organized. Each of her objects had its place, but mine always hid somewhere. She even labeled(贴标签) everything. I always looked for everything. Over time, Kate got neater and I got messier. She would push my dirty clothing over, and I would lay my books on her tidy desk. We both got tired of each other.

    War broke out one evening. Kate came into the room. Soon, I heard her screaming, “Take your shoes away! Why under my bed!” Deafened, I saw my shoes flying at me. I jumped to my feet and started yelling. She yelled back louder.

    The room was filled with anger. We could not have stayed together for a single minute without a phone call. Kate answered it. From her end of the conversation, I could tell right away her grandma was seriously ill. When she hung up, she quickly crawled(爬) under her covers, weeping. Obviously, that was something she should not go through alone. All of a sudden, a warm feeling of sympathy rose up in my heart,

    Slowly, I collected the pencils, took back the books, made my bed, cleaned the socks and swept the floor, even on her side. I got so into my work that I even didn't noticed Kate had sat up. She was watching, her tears dried and her expression one of disbelief. Then, she reached out her hands to grasp mine. I looked up into her eyes. She smiled at me. “Thanks.”

    Kate and I stayed roommates for the rest of the year. We didn't always agree, but we learned the key to living together: giving in, cleaning up and holding on.