jion in 和take part in意思比不多，但用法有差別
join in多指參加小規模的活動如“球賽、遊戲”等，常用於日常口語。如：
Come along， and join in the ball game.
一起來，來參加球賽。
Why didn't you join in the talk last night?
昨晚你爲什麼沒參加座談
三 ， take part in 指參加會議或羣衆性活動等，着重說明句子主語參加該項活動並在活動中發揮積極作用。
We'll take part in social practice during the summer vacation.
暑假期間我們將參加社會實踐。
We often take part in physical labor.
我們經常參加體力勞動。
take part in是慣用詞組，part前一般不用冠詞，但part前有形容詞修飾時，要用不定冠詞。
Lincoln took an active part in polities and was strongly against slavery.
