at a conference的用法和样例：
- Sally meets a businessman at a conference.
- To be present, as at a conference.
- Luckily, I'll be at a conference here the week before.
- B: Now I remember. We met at a conference in Tokyo last year.
- We mean to slug it out at a conference table and not in a battle.
- Kay: Oh, that was one of the topics at a conference I attended last week.