能源、环境问题是全球关注的热点问题。
(1)现阶段，人们主要利用煤、____ 和____ 等化石燃料产生的能量。
(2)“蜂窝煤”被加工成多孔形状的原因是____ 。
(3)火箭用联氨(N₂H₄)做燃料，用四氧化二氮(N₂O₄)助燃，生成物不会对大气造成污染。完成其燃烧反应的化学方程式：2N₂H₄+N₂O₄  = 3N₂ + ____ 。
(4)“转变传统观念，推行低碳生活”的主题旨在倡导节约能源和利用清洁能源，减少温室气体二氧化碳的排放。下列措施①少买不必要的衣物；②减少使用私家车次数、多乘公交车或骑自行车；③废旧电池回收再利用；④开发新能源如太阳能；⑤焚烧废旧塑料解决“白色污染”，符合该主题的是____ (填数字序号)。

①社会必要劳动时间决定商品的价值量

②电价格的大小由其在不同时段的使用价值决定

③供求关系的变化影响商品的价格变动

④人们可以运用价值规律调节经济生活

在学完全等三角形后，李老师给出了下列题目：

求证：角的内部到角的两边距离相等的点在角的平分线上．

已知：

求证：

证明：

    I asked many classmates and friends, “What do you think you will be1you grow up?”2of them told me what they would like to be in the future,3others said, “I don't know.” I'm4to hear that because I think it's bad. I think5dreams or hopes about the future will help us do better at school.

    6middle school students, it's time for us to7what we want to be in the future. If we know it better, we will know8to do it better at school. For example, if you are outgoing and like to meet people, you can be a9in the future. Then you should practice10more articles. If you're11with children and like12, you can teach English as a job in the future. And then you should work harder13English. If you want to14many interesting places, you can be a guide.

    Of course, all the15that we are learning at school will be useful in the future, so we should work hard at all of them.

一般来说，生态系统中的成分越____ ，生物种类 ____ ，自动调节能力就越 ____ ，生态系统的稳定性就越高。