雾夜狂奔
To meet the requirement (At the request) of the experts around the country, our company is going to held a 12- day seminar. We are now sincerely looking forward to your attendance.
Rabbit公主
attendtheseminarseminar研讨会属于会议一类的，包括meeting，conference等，动词用attend，表示出席的意思。participatein通常用于参加一些活动，如participateinanactivity/aparty/thegame/festivities
橘子汽水2046
attend a forum/seminar participate in a forum/seminar take part in a forum/seminar be involved in a forum/seminar 都可以。
