It is that teachers have learned from bitter experience how little history their pupils retain as they pass along the regular route.

教师们从痛苦的经历中了解到，当他们沿着常规路线前进时，他们的学生所记住的历史是多么的少。

Regular routes, known as " underground railways, " were laid out across the free states into Canada, and trusted friends of freedom maintained " underground stations" where fugitives were concealed in the daytime between their long night journeys.

被称为“地下铁路” 的常规路线穿过自由州进入加拿大，可信赖的自由之友维护着“地下车站” ，白天逃犯在漫长的夜间旅程之间躲藏起来。