下列说法正确的是（　　）

打火机给人们的生活带来了方便，如图为普通打火机的示意图，请回答下列问题；

（1）打火机的制作材料中属于金属材料的是____ ．（填物质的编号）．

（2）打火机打着火时，挡风不锈钢罩并没有燃烧起来，据此说明燃烧需要的条件之一是____ ；而将打火机的开关松开即可熄灭火焰，这种灭火方法的原理是____ ．

（3）打火机中原料是丁烷（化学式为），丁烷完全燃烧产生二氧化碳和水，写出该反应的化学方程式：____ ．

（4）用分子、原子的观点解释丁烷气体能被压缩成液体的原因：____ ．

      Traffic lights are very important for us. I think you know this. But do you know how they were born?
      Garrett A. Morgan was the father of traffic lights. He was an American. His family was very poor. He left school at the age of 14. He was clever. He always looked for better ways to do things. And he liked to make new things.
      At that time, every American wanted to have a car. The streets were full of cars. The traffic was really bad. “Why not put three lights at each corner ? They should be red_,green_,and yellow，” Morgan said , “ Let them tell cars to go or stop.” He made a timer (定时器)to change the lights.
     So we have traffic lights today .