男性，67岁，慢性咳嗽、咳痰20余年，进行性气急加重5年。1周前因感冒后病情恶化入院。血气分析（呼吸空气）示：pH7．30，PaCO₂28．6kPa（65mmHg），PaO₂6．4kPa（48mHg）。当即给予低流量（浓度）持续氧疗强调持续性氧疗是由于（）.

A. 1
B. 2
C. 3
D. 4

es the womn hve to chnge her flight in Mdrid There’s no direct flight. B．There’s no setvilble on direct flight. C．She wnts to leve tomorrow morning. D．She will contct some peoplet Mdrid.A．There’s no direct flight．B．There’s no seat available on direct flight．C．She wants to leave tomorrow morning．D．She will contact some people at MadriD．