join 参加组织或人
take part in=join in参加活动
attend参加会议
He joined us in the discussion yesterday.
他昨天参加了我们的讨论。
He joined the army two years ago。
他两年前参军了。
In early days only male athletes were allowed to take part in the Olympic Games.
在奥林匹克运动会早期, 只有男性运动员才能参加比赛。
I shall be attending the meeting.
我会参加会议。
join + sb.
take part in + 大活动或者大组织
join in + 小规模活动或组织
attend 一般指参加会议