My poor pet dog is seriously ill. I' m afraid it is ______ to die before long. [ ]

A. certain        

B. likely        

C. obvious  

D. probable

种类较少且无论雌雄、无论幼体成体全为寄生的淡水鱼类甲壳动物性病原是（）

A.锚头鳋

B.中华鳋

C.鱼鲺

D.鱼虱