slack coal

例句：

1. 1. The mineis producing a lot of slackcoal.
   矿井正在生产大量的松懈煤。
2. 2. Thecoal mine needs to be tightened upto prevent slack coal from beingreleased.
   煤矿需要被加强以防止松懈煤的释放。
3. 3. The slack coal wascausing the fire to spread rapidly.
   松懈的煤导致火势迅速蔓延。