I've seen this written in a course book: ' Who is writing to who?'.
Shouldn't it be : 'Who is writing to whom?'
Thank you in advance.
***NOT A TEACHER***Yes, you are 100% correct. Here in the States, some people are "afraid" to use "whom" because (a) they don't understand the rule or (b) they understand the rule but don't want to seem snobbish.