Most children take part in after-school clubs.

问题描述:

Most children take part in after-school clubs.
以前学过加入俱乐部是用join
为什么本句中用take part in

"Join" means to become a member of the club
"take part in" or "paticipate in" mean to take part in the activities of the club, it does not necessarily mean to join the club.
For example, a player can join a Ping-Pong club to play there. However, some non-member players may just play there for one evening for $10.