单项选择题
A.PaO2≤8kPa(60mmHg),PaCO2≥6kPa(45mmHg),SaO2<90%
B.PaO2≤8kPa(60mmHg),PaCO2≥6.7kPa(50mmHg),SaO2<90%
C.PaO2≤6.7kPa(50mmHg),PaCO2≥6.7kPa(50mmHg),SaO2<85%
D.PaO2≤6.7kPa(50mmHg),PaCO≥8kPa(60mmHg),SaO2<85%
E.PaO2≤6.7kPa50mmHg),PaCO2≥6.7kPa(50mmHg),SaO2<90%