naphthene index

例句：

1. 1. The naphthene indexis a measure of the concentration of naphthalene in petroleum.
   萘指数是衡量石油中萘浓度的一种指标。
2. 2. The naphthene index hasbeen used to predict oil production in thepast.
   萘指数在过去曾被用来预测石油产量。
3. 3. The naphthene index isan important factor in determining the quality ofpetroleum products.
   萘指数是决定石油产品品质的一个重要因素。