—Excuse me, is this your backpack?

—_____[ ]

A. Sorry, I don't know                    

B. Yes, it is. Thank you

C. Your backpack is in my room            

D. It's black

微机视屏显示终端(VDT)操作人员，由于静态负荷，频繁操纵键盘，头部经常转动，手臂悬空，最易引起

A．四肢骨关节炎

B．滑囊炎

C．颈肩腕综合征

D．骨关节坏死

E．垂腕