气道闭合压正常值为()
A.-4~-6cmH2O
B.-2~-4cmH2O
C.0~-2cmH2O
D.0~2cmH2O
E.2~4cmH2O
参考答案:B
It’s dangerous for us _____ trees.[ ]
A. to climb
B. climbing
C. climb
D. climbed
低温库保温工况的热负荷主要是:()。
A.喷物热
B.换气热
C.呼吸热
D.渗入热