(2013·江苏苏中三市一模)—I'm afraid it's going to rain this afternoon.

—________ Look at the dark and cloudy sky.

A．Not really.

B．Is it?

C．Why not?

D．I guess so.

氧疗可通过提高吸入气中的氧浓度，缓解或纠正机体缺氧状态。以下哪些是氧疗的适应证（）。

A.胸腹部手术后

B.中枢神经系统疾病

C.药物镇静状态

D.慢性肺部疾病

E.严重贫血病人