题干

实验室可利用乙醇、铜或铜的化合物制备乙醛,下图是某兴趣小组设计的实验装置,右边的反应装置相同,而左边的气体发生装置不同,试管C中装有水.试回答:

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同类题5

阅读下面的短文,然后根据短文内容,在每小题所给的四个选项中选出最佳选项。
                                                                                          C
  “How are you?” is a nice question. It's a friendly way that people in the USA greet each other. But “How are you” is also a very unusual question. It's a question that often doesn't need an answer. The person who asks “How are you?” hopes to hear the answer “ Fine”, even if the person's friend isn't fine. The reason is that “How are you?” isn't really a question and “Fine” isn't really an answer. They are simply other ways of saying “Hello” or “Hi”.
    Sometimes, people also don't say exactly what they mean. For example, when someone asks “Do you agree?” the other person might think, “No, I disagree. I think you’re wrong…” But it isn't very polite to disagree so strongly, so the other person might say “I'm not sure.” It's a nicer way to say that you don't agree with someone.
    People also don't say exactly what they are thinking when they finish talking with other people. For example, may talks over the phone finish when one person says “I've to go now.” Often, the person who wants to hang up gives an excuse “Someone's at the door.” “Something is burning on the stove.” The excuses might be real, or not. Perhaps the person who wants to hang up simple doesn't want to talk any more, but it isn't polite to say that. The excuse is more polite, and it doesn't hurt the other person.
    Whether they are greeting each other, talking about an idea, or finishing a talk, people don't say exactly that they are thinking. It's an important way that people try to be nice to each other, and it's part of the rule of the game of language.