But for the fact that the firefighters _____ at the spot in time, more people ______ their lives in the fire.

A．arrived; died

B．had arrived; would lose

C．arrived; would have lost

D．has arrived; could have lost

病历摘要：患者男性，62岁，因右下肺癌拟行右下肺叶切除术。身高1.67m，体重65kg，血压20／12kPa，心率64次／分。既往有慢性支气管炎，阻塞性肺气肿，有七年冠心病病史，二年前有心肌梗塞，近年无心绞痛发作。能进行正常生活与工作。心电图检查无异常。肝肾功能生化检查各项正常。

关于通气／血流比值（V／Q）下述哪些是对的？（）。

A.正常人全肺平均通气／血流比值为0.8-0.9

B.正常人坐位时的V／Q，肺上部低，下部高

C.V／Q增高时，表示生理短路增大

D.V／Q降低时，表示生理死腔增大

E.出血性休克，血压降低，肺栓塞等是肺泡死腔量增大的原因