每次考试来临的时候，约翰就变成了一只夜猫子，但这并不是一个好的学习方法。
[误] John becomes a night cat every time the examination is coming. However, this is not a good way to learn.

[正] John becomes a night owl every time the examination is coming. However, this is not a good way to learn.

注：owl是“猫头鹰”的意思，即一种深夜不睡，睁一只眼，闭一只眼，准备随时捕捉田鼠的动物。英语中用night owl来比喻经常熬夜的人，就像我们习惯用“夜猫子”一样。不论叫你“夜猫子”还是a night owl，“开夜车”（burn the midnight oil）总是免不了的。