The octane rating tells you how much the fuel can be compressed before it’ll ignite without a spark.

辛烷值告诉您在没有火花的情况下点燃燃料之前可以压缩多少燃料。

That number on the pump is called an octane rating, and it tells you how much the gasoline can be compressed before it’ll just ignite.

泵上的数字称为辛烷值，它告诉您汽油在点燃之前可以压缩多少。