56岁，男性，因多发关节肿痛23年来诊。

还应做哪些检查（）

A.（抗）角蛋白抗体

B.（抗）dsDNA抗体

C.血沉

D.C反应蛋白

E.类风湿因子

F.抗0

G.尿酸

H.HLAB27

I.（抗）CCP抗体

Personally, the job as a teacher _____ be challenging, for I sometimes _____ deal with some smarter but less diligent students.

A．can; have to

B．may; can

C．has to; may

D．ought to; must