No mere ferule will answer for this offence.

没有简单的 ferule 可以为这种罪行负责。

No threats of the ferule would provoke Harry to learn in an idle fit, or would prevent George from helping his brother in his lesson.

来自戒尺的惩戒对游手好闲的哈里无济于事；同时，亦无法阻止乔治协助弟弟躲避用功。