Sample Set of Fuel
| 1 | Natural gas | 7 | Olefin |
| 2 | Rice straw | 8 | Solid alcoho; |
| 3 | Firewood | 9 | Brown coal |
| 4 | Carbon | 10 | Asphaltum |
| 5 | Flammable | 11 | Petroleum |
| 6 | Coal | 12 | Coal ball |
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