A.環(huán)境改良劑B.生物制品C.代謝改善和強壯漁藥D.殺蟲驅(qū)蟲藥
A.繼發(fā)性感染B.主動經(jīng)皮感染C.被動經(jīng)皮感染D.混合感染
A.2mg/LB.4mg/LC.8mg/LD.20mg/L