题干

在点燃的条件下,A和B反应生成C和D.反应前后分子种类的变化如图所示:

(1)A、B、C中属于单质的是____  (填字母).

(2)一个B物质的分子是由____ 个原子构成的,B物质中氮元素的化合价是____  .

(3)若D为空气中体积分数最大的气体,则该反应的基本反应类型是____ .

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答案(点此获取答案解析)

A,4,-3,置换反应

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    Author Elizabeth Becker says we have a responsibility to respect the places we visit. Some basic rules still hold, such as not travelling at busy times and taking fewer trips but making them longer. The best and easiest way to be a responsible traveler is to use common sense and go local.

    Respect traditions. Read about the culture and traditions of the places you visit. Understand the local culture and customs to avoid making any mistakes or upsetting the local people. For example, dress properly when you visit temples and don’t eat or talk loudly in religious(宗教的)sites. It’s also important to respect the local environment. If you visit a beach, leave seashells where you find them and try not to catch fish while swimming.

    Learn the language. Nobody expects you to become fluent, but try to learn some basic phrases such as “please” and “thank you”. You’ll be amazed at how much nicer and more helpful people will be if they know you’re making an effort to get involved with their culture.

    Spend local. Stay away from international hotels and restaurants run by foreigners. By using local guides, buying local products and staying in family run hotels, you’re not only giving back to the community, but you also get a real sense of the country you’re staying in and the people who live there.

    Bargain fairly. Always be polite when you try to get a lower price. Sometimes goods at a local market can seem overpriced. Nobody likes to be cheated and it may be fun to bargain, but remember that for the local people bargaining it may not be a game. For some of them, their business is their only source of income. So try not to be too rude when bargaining.

    Don’t litter. In some countries, getting rid of waste is a big problem, so don’t throw rubbish on the ground. Doing so is harmful to the environment and unpleasant for others. Hold on to your rubbish until you find a bin.

    Save water. Even in some of the most developed countries, water shortages are a reality. Tourists who take 10-minute showers and leave the taps running aren’t making things any better.