—What’s Jim doing now  ?

—He ________ TV with his father in the living room.

A．is watching

B．are watching

C．is watch

D．are watch

以下血清中何种成分有助于皮肌炎的早期诊断（）

A.乳酸脱氢酶

B.肌红蛋白

C.还原型血红蛋白

D.肌酸激酶