—Mr. Gao, I don’t understand the meaning of this new word.

—You can __________ the word in your dictionary. I believe you can understand it well.

A．look at

B．look for

C．look up

D．look after

女性，48岁。左肩痛3个月，呈逐渐加重，不能梳头，左肩关节外展、后伸受限，三角肌萎缩，无手臂麻木感。最可能的诊断是（）。

A.颈椎病

B.肩部肿瘤

C.肩周炎

D.肩关节结核

E.风湿性关节炎