单项选择题
A.3~300Hz B.30~3000Hz C.1~1000Hz D.1~2000Hz E.任意频率
A.不到0.1%的尘粒沉积在肺内 B.0.1%~0.3%的尘粒沉积在肺内 C.1%~3%的尘粒沉积在肺内 D.10^~30%的尘粒沉积在肺内 E.10%~50%的尘粒沉积在肺内
A.15% B.7% C.5% D.3% E.2%