John wants to _  __ the Music Club and becomes a new member of it.

A．join

B．join in

C．will join

D．take part in

以下哪一项是对类风湿性关节炎的正确描述()

A．全身性疾病

B．原因明确

C．主要为大关节病变

D．多呈非对称性

E．病程短