单项选择题
A.5:1 B.5:2 C.15:1 D.15:2 E.30:2
A.4~10cmH2O B.5~12cmH2O C.6~14cmH2O D.5~10cmH2O
A.1%~2% B.2%~3% C.3%~4% D.4%~5%
A.30℃~32℃ B.31℃~33℃ C.32℃~35℃ D.33℃~36℃
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