单项选择题
A.12 B.15 C.30 D.60
A.10/5/5 B.10/7/7 C.5/10/5 D.5/5/10
A.(75%~85%)nH、(70%~80%)nH B.(75%~85%)nH、(60%~70%)nH C.(80%~90%)nH、(70%~80%)nH D.(80%~90%)nH、(60%~70%)nH