I'm a little bit puzzled with some relatives pronouns, when they don't go and when the preposition is used at the end, so I made myself some transformations that I'd like you to check, I don't know if they are correct:

Those are the girls I told you about.
Those are the girls about whom I told you.

He's is a difficult man to live with.
He's a dificult man with whom to live.

The children in the family I was staying with treated me well.
The children in the family with whom I was staying treated me well

There isn't enough snow to ski on.
There isn't enough snow on which to ski.

A chair is something you sit on.
A chair is something on which you sit on.

I forgot the date you arrived on.
I forgot the date on which you arrive.
You made a typing error in each of the fifth and sixth sets, but otherwise the grammar is fine, and the second member of each set is very formal.
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I'm sorry MrM, but I can't see the error in the fifth. What is it?
You have two 'on's in the second sentence of the fifth pair. I don't think you intended to retain the second 'on'.
well you have some mistakes:
in nunber one the answere is : those are the girls I told you about.
second: He is a difficult man to life with
third: the children in the family who I was with treated me well.
number four: there isnt enough snow where I can Ski.
# 5 : a chair is something where you can sit or a chair is somethig in which you can sit (in this one Im not sure).
last one : I forgot the day when you arrived.
NOTE: I am not sure about this answeres the problem is that my original toungue is spanish, but this is something i have learned in my school, I whis this can help you ..!! =)
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