1. The moderator of the conference had an argument with the attendees.2. He became the host of the popular show "Who Wants To Be A Billionaire?" when he was only twenty years old.
 moderator host hostess emcee co-hostHost指男性; hostess指女性，而 co-host 指副主持人。emcee 是司儀的意思，司儀不一定是主持人