coal sear

例句：

1. 1. The coal sear is a byproduct of the coal-fired power plant.
   煤焦油是燃煤发电厂的副产品。
2. 2. The coal sear has been used in many industrial processes.
   煤焦油在许多工业过程中被使用。
3. 3. The coal sear is a complex chemical compound with many uses.
   煤焦油是一种复杂的化学化合物，用途广泛。