They are free to join.

他们随时可以加入。

youdao

Me: Microsoft are free to join the OASIS SCA activities at any time and we would welcome them.

ME：微软可以在任何时间加入OASIS SCA活动，我们会欢迎他们。

youdao

Some sites such as OkCupid and Plentyoffish are free to join and make most of their money from advertising.

有些网站如okcupid和Plentyoffish，加入是免费的，他们主要通过广告赚钱。

youdao

He in back in training and working pain-free, although he has yet to join in sessions with the first-team squad.

BBC: Wojciech Szczesny

Arthur X-Man, who quit his job on a free-range chicken farm in eastern England to join the movement, joked that he and other occupiers felt a little like refugees, and said they were searching for a new place to Occupy.

WSJ: Occupy Movement's Version of the Odd Couple Unfolds in London

He showed no disappointment in his playoff-free two seasons with the Sabres after waiving his no-trade clause to join the high-priced disappointments.

WSJ: LA Kings acquire D Robyn Regehr from Buffalo