Who vs Whom

Most people as I did, don't really grasp the whole concept of the usage of the words who and whom. The way I used whom was only if it sounded right, and I would use who for everything else. Just Recently I had to do a "Grammar Schmammar" presentation on who vs whom. If I would have never chose the who vs who concept, today I probably still wouldn't know the right usage of who and who. Once you learn it, it is very easy, well to me it is.I pulled up a video for the class to watch on the subject, and I think it helped out a lot. The video is what helped me to learn it. There is a trick used in the video to determine when you use who and who. If you can replace the sentence with he or she, then more than likely you should use who. If you can replace the sentence with the word him or her, than more than likely you can replace the sentence with whom.Here is an example of both of them: Who/Whom did you go to the store with? You would answer this question by saying "I went to the store with him" therefore you would use the word Whom. Another example is: Who/Whom is a lawyer? You would answer this question by saying "He is a lawyer" therefore you would use the word who. As you can see with the he,she/him,her concept this can be quite easy.