purification of kerogen

例句：

1. 1. Theextraction of kerogen from oil isa complex process.
   从油中提取石油沥青是一个复杂的过程。
2. 2. The kerogenin the rock has been found to bea source of energy.
   岩石中的石油沥青被发现是一种能源来源。
3. 3. The kerogenin the rock can be used to producegas and oil.
   岩石中的石油沥青可以用于生产气体和石油。