A.0.08db/個(gè) B.0.10db/個(gè) C.0.20db/個(gè) D.0.25d/個(gè)
A.1:2.5 B.1:3 C.1:3.5 D.1:4
A.0.5 B.0.65 C.0.7 D.0.95