extra heavy concentration

例句：

1. 1.The extra heavy concentration of the solution made it difficult to filter out impurities.
   溶液的超重浓度使得过滤杂质变得困难。
2. 2.The extra heavy concentration of the oil caused the engine to overheat.
   油的超重浓度导致发动机过热。
3. 3. In order to improve the performance, the engineers decided to reduce the extra heavy concentration in the fuel.
   为了提高性能，工程师们决定减少燃料中的超重浓度。