join是“加入某个党派或社会团体，从而成为该党派或团体的一员”而join in意思是“参加某项运动或活动”，例如参加讨论、游行、罢工等。
“参加工作、会议”自然要在其中发挥作用,要以主人翁姿态,所以一般用take part in，attend主要指“到场”或“出席”等。participate是不及物动词,后接in,指参与活动并积极从事工作,是正式用语。
1、The island is joined to the mainland by a bridge.
岛上有座桥与大陆相连。
2、The two estates join at the foot of the hill.
这两处房地产在山脚下相毗连。
3、If you join the club, you must abide by its rules.
你参加这个俱乐部就得遵守其规章。
4、He was asked many times to join the party, but he always kept his distance.
人家好几次要他参加那个政党，但他的反应总是很冷淡。
5、He joined us in the discussion yesterday.
他昨天参加了我们的讨论。
2、I hope that everyone will be able to join in the fun
我希望每个人都能够加入进来，玩得开心。
3、He started to sing and I joined in.
他开始唱起歌来，然后我也跟着唱起来。
4、You don't have to join in; there are more than enough people on the job already.
人够多了，您就不用插手了。
1、If you want knowledge, you must take part in the practice of changingreality.
你要有知识，你就得参加变革现实的实践。
2、You can take part in activities from canoeing to bird watching.
你可以参与从划独木舟到观鸟等各种活动。
3、Cadres have gone down to different grass-roots units to take part in manual labour.
干部们分别下基层参加劳动去了。
1、Thousands of people attended the funeral
数千人参加了葬礼。
2、They attended college together at the University of Pennsylvania.
他们一起就读于宾夕法尼亚大学。
3、The staff will helpfully attend to your needs
工作人员会帮忙满足您的需求。
1、They expected him to participate in the ceremony
他们希望他参加典礼。
2、Over half the population of this country participate in sport.
这个国家一半以上的人口参加体育锻炼。
3、He planned to participate in the demonstration, but then he got cold feet.
他打算参加示威，但后来临阵退缩了。