| 1 | "Shale gas, " he says. | |
| 2 | We can extract oil from shale. | |
| 3 | We must find economical methods for extracting oil from shale. | |
| 4 | The new process extracts oil from shale. | |
| 5 | Recent technological breakthroughs have made natural gas extracted from shale more available, but that will not eliminate the use of coal. |
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