Venturi面罩的吸入氧浓度可调范围为
A.25%~50%
B.24%~50%
C.21%~35%
D.21%~55%
E.52%~100%
参考答案:B
This is _____ case. That' s _____ eraser. [ ]
A. a; an
B. an; an
C. a; a
D. an; a
疫区来货入境时,货主或其代理人(如司机)应向检验检疫机关逐次申报并接受相应卫生处理( )