第一，迷你对话
A: Tom is late again.
Tom有迟到了。
B: He's at it again, isn't he?
他是明知故犯，不是吗？
A: You should give him a lesson.
你该教训下他了。
B: But he's only a tartar.
但是，他是个难对付的人。
第二，地道表达
at it
1. 解词释义
At it的意思是 involved in an action, activity, or pursuit vigorously, exhaustively, or determinedly。（积极地，彻底地，坚决地从事某事）。
2. 拓展范例
E.g. I studied really hard for this test; I was at it all night.
E.g. I wish those dogs would quit barking, they've been at it since the sun came up!
我希望这些狗停止吼叫，他们从太阳升起的时候就开始叫起来了。
E.g. Be up and at it before sunrise.
日出前起来做吧。
E.g. We do have internal leaks. We have caught some people at it.
我们内部确实有人泄密。我们已经抓住一些干这种事的人。
第三，好词妙语
give sb. a lesson：教训某人
E.g. If you keep on pissing my sister around, I'll give you a lesson.
如果你继续要糊弄我妹妹的话，我一定要教训你。
E.g. You see! He didn't even give me food this morning again. I will give him a lesson.
你看！他早上又没有给我食物。我要给他个教训。
