Walter offered us a lift when he was leaving the office, but ________our work, we declined the offer.[ ]

A．not finished  

B．not having finished

C．finished  

D．having finished

诊断气胸最重要的检查方法是（）

A.X线胸片检查

B.肺功能检查

C.胸部CT

D.胸腔内测压

E.支气管镜