[FONT=바]I appreciate your kind and detailed explanation. I have looked up it in some grammar reference books and come to the same conclusion as your comment. Having been taught that "none' means "not one", I thought that none is followed by singular verb as a natural result. However, in many grammar books which I referred to, most of the example sentences that have "none" as a subject have plural verb. With your comment, I have come to teach it to my students more clearly. Thank again your comment. Peace and joy to you. [/FONT]