支气管哮喘患者发生I型呼吸衰竭最主要的机制是（）

A肺泡通气量下降

B通气/血流比例失衡

C弥散性功能障碍

D肺内分流

E氧耗量增加

Deballasting a double bottom has what affect on KG?（）.

A.KG is increased

B.KG is decreased

C.KG is not affected

D.KG increases at light drafts and decreases at deep drafts