题干

关于烷烃性质的叙述中,不正确的是(     )

A:烷烃同系物随相对分子质量增大,熔点、沸点逐渐升高;常温下的状态由气态递变到液态,相对分子质量大的则为固态

B:烷烃同系物都能使溴水、KMnO4溶液褪色

C:烷烃跟卤素单质在光照条件下能发生取代反应

D:烷烃同系物的密度随相对分子质量增大逐渐增大

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B

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    All over the world mothers and fathers teach their children manners. Other children may have manners that are not like yours. There are all kinds of manners.

    Many years ago, children who had good manners were seen and not heard. They kept quiet if grown-ups were talking. Today, well-mannered children have more freedom.

    Sometimes good manners in one place are bad manners in other places. Suppose you are a visitor in the land of Mongolia. Some friends ask you to eat with them. What kind of manners do they want you to have? They want you to give a loud “burp(打嗝)” after you finish eating. Burping would show that you like your food. In some countries, if you give a loud burp, you are told to say “Excuse me, please.” In many places people like to eat together. But in some parts of Polynesia it is bad manners to be seen eating at all. People show good manners by turning their backs on others while they eat. What are manners like in an East African town? The people try not to see you. They are being polite. You may see a friend. He may not see you at all. If you are polite, you will sit down beside him. You will wait until he finishes what he is doing. Then he will talk to you. Suppose you visit a friend in Arabia. You should walk behind the other tents until you come to his tent. If you pass in front of the other tents, you will be asked into each one. The people will ask you to eat with them. And it is bad manners if you say no.

    Manners are different all over the world. But it is good to know that all manners begin in the same way. People need ways to show that they want to be friends.