You sly old devil! How long have you known?

你这个老滑头！你知道有多久了？

《牛津词典》

Ah! You mysterious old devil, I've got you, that I have!

啊！神秘的鬼老头，今天可落在我掌心里了，哈！

youdao

Ah! You mysterious old devil, I've got you, that I have!

啊！神秘的鬼老头，今天可落在我掌心里了，哈！

youdao