A.1 B.2 C.3 D.多种
A.大气污染 B.化学污染 C.物理污染 D.微生物污染
A.30 B.50 C.60 D.100
A.500；50；50 B.1000；100；100 C.1500；100；100 D.1500；150；150
A.1/2 B.1/3 C.1/4 D.1/5
A.10 B.20 C.30 D.40
A.1 B.3 C.5 D.10
A.10 B.15 C.20 D.25
