I read this in a book:
We do not use whom when the preposition is in this position:
- Mr. Lee, who I spoke to at the meeting, is interested in our proposal.
(not Mr. Lee, whom I spoke to ...)
But, what I know from here: how-can-one-differentiate-between-who-and-whom, Who is used when you are talking about the subject and Whom is used when we are talking about an object.
Is it the example above we're talking about object? So why not whom? Is it because a sentencd that has the preposition can't use whom?