The teacher _____ the students how to improve their writing skill since last term.

A．has told

B．is telling

C．has been telling

D．will have told

类风湿关节炎最常见的关节外表现是

A．肺间质病变

B．肺动脉高压

C．类风湿血管炎

D．类风湿结节

E．蛋白尿