下载APP
举一反三
【单选题】线虫纲寄生虫的生活史（）
A.
都属土源性蠕虫联
B.
都属生物源性蠕虫
C.
多数是生物源性蠕虫，少数是土源性蠕虫
D.
少数是生物源性蠕虫，多数是土源性蠕虫
E.
以上到对
【单选题】细菌性烂鳃病与寄生虫性烂鳃病的相似症状是( )
A.
病鱼体色发黑，尤以头部为甚，鳃上黏液增多，魍丝肿胀，严重时鳃丝末端缺损，软骨外露
B.
发病晚期出现"开天窗"
C.
鳃盖充血、出血
D.
上下颌红肿
【单选题】B Most of the animals have little connection with animals of a different kind, unless they hunt them for food. Sometimes, however, two kinds of animals come together in a partnership whi...
A.
birds and parasites
B.
birds and sheep
C.
parasites and sheep
D.
sheep, birds and parasites