If you look at someone or speak to someone de haut en bas, you do it in a way that shows you think you are superior to them. De haut en bas is French for "from high to low".

She looked at me de haut en bas and asked "And where do you come from?" 她傲慢地看着我，问道：“那么你是哪里人？”

He had a very de haut en bas approach to teaching. 他秉持一种居高临下的教学方式。