能源的合理利用与开发是非常重要的．

（1）将煤作为燃料，主要是利用碳元素与氧反应放出的______；有时燃气灶或煤炉会产生黑烟，是因为燃料中的碳不能______燃烧．

（2）汽车用柴油是由______加工的产品，汽车尾气中氮的氧化物直接排放到空气中，溶于雨水会形成______．化石燃料对环境的影响不容忽视，人们正在开发和利用的新能源之一是______．

完成句子，使改写后的句子完整，并与原句意思相符，注意每空只填一个单词。

1. They were winners in the match finally.

   They were winners in the match __________ ___________.

2. He didn't come because he was ill yesterday.

   He didn't come __________ __________his __________yesterday.

3. I wasn’t at school last week.

   I was __________ __________school last week.

4. Tom was born in 1990. Jack was born in 1990,too.

  Tom is __________ __________ __________Jack

5. What is the meaning of "xchange" ?

  What do you __________ __________"exchange" ?