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____ ．

   I came to Australia last year and I  ____   (落下) in love with it. I can see the ____  （明亮的）sunshine everywhere. At the beginning of this ____  (学期), I couldn't understand the teacher in class. Her English was quite different from what I'd heard in class at home. I;m____(幸运的) enough because my classmates are really friendly and helpful . It's____  (令人惊讶的) that I got an A last week. My science teacher is ____（也）good. She said that I was____ （勤勉的）. I dedided to work harder and get good ____（成绩）.After class I always play soccer with ____  (他们).  This is a great ____ （机会）for me to study in Australia .

“低碳生活”是指减少能源消耗、节约资源，从而降低二氧化碳排放的一种时尚生活方式．下列不符合“低碳生活”这一主题的做法是（　　）

下列重要的经纬线穿过我国的是：