MCQOPTIONS
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| 1. |
Underground coal mines are in principle ventilated by exhausting system, so that |
| A. | spontaneous heating risk is reduced |
| B. | fumes can be quickly removed in case of an underground fire |
| C. | build-up of methane concentration is decreased |
| D. | cool and fresh intake air can enter underground |
| Answer» D. cool and fresh intake air can enter underground | |