Subject + 加入 + Organization/Group
The verb 加入 (jiārù) means "to join," "to enter," or "to become a member of" and is used when someone becomes part of a group, organization, or activity. It is followed by the entity being joined.
他去年加入了学校的篮球队。
tā qùnián jiārù le xuéxiào de lánqiú duì.
He joined the school basketball team last year.
越来越多的年轻人想加入这个志愿者组织。
yuèláiyuè duō de niánqīngrén xiǎng jiārù zhège zhìyuànzhě zǔzhī.
More and more young people want to join this volunteer organization.
你有兴趣加入我们的读书会吗?
nǐ yǒu xìngqù jiārù wǒmen de dúshūhuì ma?
Are you interested in joining our book club?