After living with his grandparents in the countryside fort en years, the boy returned to

The big city____his parents worked.

A．which

B．where

C．that

D．when

男，25岁，脑炎患者，呼吸不规则，并有暂停，神志不清。血气分析：PaO5.33kPa(40mmHg)，PaCO4.67kPa(35mmHg)。氧疗时宜采用()

A．持续低流量给氧

B．鼻塞低浓度间歇给氧

C．高浓度给氧

D．鼻导管低浓度给氧

E．鼻塞给氧