coal quality

例句：

1. 1. The coal quality is crucial for the power plant's efficiency.
   煤炭质量对电厂的效率至关重要。
2. 2. The coal quality of this mine is among the best in the region.
   该矿的煤炭质量是该地区最好的之一。
3. 3. The coal quality will be tested before it is shipped to customers.
   在将煤炭运送给客户之前，将会对其进行质量测试。