if a already submit one article to directory A. should i need to submit the same article to directory B, C etc..?
IMO, if you submit a good article to ezine, it is going to do pretty well. If you want to amp up the link juice, you can submit other articles to the other directories and link to your ezine article. That should push your ezine article towards the top of google in rapid fashion. Just make sure, in your other directory articles, that you use your targeted keywords as anchor text links to the ezine article.
This is what your looking for: article directory list EDIT: Wow how the fk did that happen, I was not meant to post that here, sorry.