join,join in,take part in的区别

join加入组织，团体，党派等，有作为其中的一个成员的含义。
join也可以加人，表示和某人一起参加某活动。既join sb. in (doing) sth.
如：
It's two years since he joined the club.
Will you join us in the discussion?

而join in 则是加入一种具体活动，
如：
join in the search
join in the group singing (注意，有别于join the singing group 这个是组织 )

attend 则是加入会议，上课，婚礼，葬礼等
如attend the meeting
attend the class

take part in 指参加会议或群众性活动等，着重说明句子主语参加该项活动并在活动中发挥作用。如：
We'll take part in social practice during the summer vacation.
The Swiss didn't take part in the two World Wars.
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