作为能源的化石燃料中，常用的固体燃料是 ______，液体燃料是 ______，气体燃料是 ______．化石燃料在利用的过程中对环境的污染，主要是燃烧时产生的 ______、______及 ______所造成的．能源危机迫使我们开发新能源，你认为可开发的新能源有 ______、______等．
化石燃料在地球上的蕴藏量是有限的，并且会产生有害的气体污染环境．所以我们既要节约和综合利用现有的能源的同时，要不断地开发新能源，如：太阳能、风能、核能等可以替代的新能源．
故答案为：煤、石油、天然气；CO2；CO；SO2；氢能源、太阳能、风能、核能等．
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| We can see walls everywhere in the world . But the Great Wall of China is the 1 of all. The Chinese call it "the Ten-thousand-li Great Wall". It is more than 6,000 kilometers. It is 4-5 meters 2 . In most places, five  horses or ten 3 can walk side by side.When you visit the Great Wall, you can't 4 wondering how the Chinese were able to build such a great wall thousands of years ago. 5 any modern machines, it was really very difficult to build it. They 6 to do all the work by hand. It 7 millions of men hundreds of years to build it. The Great Wall has a history of over two thousand years. The king began to build the first parts of it around two thousand seven hundred years 8 . Then Qin Shihuang had all the walls joined up. He thought that could keep the 9 out of the country. Today the Great Wall has become a place of interest. Not only the Chinese people 10 people from all over the world come to visit it. | ||||
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