join是指加入某个group、club或者organization或者其他的团体或者协会，强调“个人加入到集体中”。join in是指参与某个活动，等于take part in。
join双语例句
1.Hi, Mike. We're having a party tonight, wanna come join us? You can bring your girlfriend.
嘿，麦克。我们今晚有个派对，你想加入我们吗？你可以带你的女朋友一起来。
2.I'll join you later.
我过一会儿来找你。
3.Organizers expect up to 300,000 protesters to join the march.
组织者预计将有多达30万名抗议者参加这次示威游行。
4.`And' is frequently used to join two sentences.
and常常用于连接两个句子。
5.Occasionally friends will join in, interposing remarks as to the probable worth of the article.
朋友们也会偶尔就这篇文章的可能价值插话谈谈意见。