双氰胺结构简式如图．

（1）双氰胺的晶体类型为 ____．

（2）双氰胺所含元素中， ____ （填元素名称）元素基态原子核外未成对电子数最多．

（3）双氰胺分子中σ键和π键数目之比为 ____

一张纸上画了一只鸡、一头牛和一片草地，要求把这三样东西分成两组，你会怎么分呢？实验表明，美国孩子更喜欢把鸡和牛分在一组，中国孩子则倾向于把牛和草地分在一组。心理学家认为，美国人善于分析不同物体各自的特征，牛和鸡都属于动物，因此分在一起；中国人则把不同物体之间的联系看得更重，因为牛吃草，所以把牛和草地分在一起。这说明（   ）

（2015•包头）下列说法正确的是（　　）

根据短文内容，从短文后的选项中选出能填入空白处的最佳选项，选项中有两项为多余选项。

    We've all experienced peer pressure (同伴压力). It happens to everybody. However, people have different reactions. Confident people refuse to do things they don't want to do, but shy and anxious people often give in. It may be because they want to be liked. It may be because they worry that their friends will make fun of them, or perhaps they're just curious about trying something new. ____

    It's hard being the only one who says no and the question is: how do you do it? ____ If you think that missing maths, or smoking, or going somewhere you know your parents wouldn't like is a bad idea then the answer is simple: don't do it. It's your decision, nobody else's. You don't need to be aggressive. You don't need to shout and scream, but you must be confident and you must be firm. You need to say, “No thanks. I don't want to do that.”

    Being on your own against everybody else is very hard, so it can really help to have at least one other peer, or friend, who will say no too. ____ You want friends who will support you when you're in trouble. You don't want people who will always agree with the majority. Remember, the most popular people aren't always the most trustworthy.

____ — You can learn a lot from people your own age. They can teach you great football skills or the best way to do your maths homework. They can recommend music and advise you on fashion. And don't forget you can tell them things too, and that always feels great. So, find friends who have similar interests. And remember, friendship isn't about feeling depressed and guilty. ____