join this charity walk中"join"是不是应该改为"join in"

join this charity walk中join是不是应该改为join in join a charity walk join in the charity work还是join the charity walk there is a charity show this weekend,would you like to join us?此句中去掉us不行吗? there a charity show this weekend.would you like to join us?填,will be 还是is charity charity 英语书上一个句子People over 18 can group themselves into a team of four and join this charity walk我觉得group与themselves之间加一个by,到底可不可以,理由? shall wa play basketball this afternoon是什么意思 amy said that she was not old enough to join the charity walk(同义句） amy said that she was——— ——— ——— join the charity walk I like to join this group I like to join this group Who wants to join this English group? Shall we ___ this singing?---That's a good idea.Let's ____ them.( )A.join in,join in B.join,join C.join in,join D.join,join in join join join join