去掉乱七八糟的,只剩下____ a club or group is easier.Join a club or group作为主语,等同于It is easier if you join a club or group,而不同于It's easier to join a club or group.后者是表示加入一个俱乐部很容易.
其实这不是语法问题,而是语义问题,原本他是想说：Join a club or group is an easier way for you,because you can talk with those guys who like the same things.
如果选To join或Joining都表示“加入一个club或group是一件容易的事”,这不符合原意