The problem seems to be one of "almost synonyms."
You replace thing A by substituting thing B. The general gist is the same; B is where A was. Sloppy grammer doesn't notice the details, that each verb has a different object in the operation. Sloppy logic then states the same general idea = the same meaning = interchangable verbs. (Did I get the grammatical terms right? I was of the generation that didn't study grammer.)

edit Unfortunately

Last edited by Zed; 04/05/2007 12:40 AM.