求解PP2上的一道阅读题求大神帮助

The most plausible justification for higher taxes on automobile fuel is that fuel consumption harms the environment and thus adds to the costs of the traffic congestion. But the fact that burning fuel creates these “negative externalities” does not imply that no tax on fuel could ever be too high. Economics is precise about the tax that should, in principle, be levied to deal with negative externalities: the tax on a liter of the fuel should be equal to the harm caused by using a liter of fuel. If the tax is more than that, its costs (including the inconvenience to those who would rather have used their cars) will exceed its benefits(including any reduction in congestion and pollution).+ j 红色部分是什么意思啊

双重否定表示肯定，你把not 和 no 同时去掉，就是说“ 但是事实是burning fuel产生的这些negative externalities表明tax可能非常高！”