How is coal extracted from the earth? what are the two correct answers.
1. by drilling wells
2. by surface mining
3. by underground mining
4. by heating and boiling it
5. by hydraulic fracturing
2. by surface mining
3. by underground mining
1. by drilling wells
2. by surface mining
3. by underground mining
4. by heating and boiling it
5. by hydraulic fracturing
3. by underground mining