A.循環(huán)器官B.排泄器官C.呼吸器官D.消化器官
A.鉤介幼蟲(chóng)B.面盤(pán)幼蟲(chóng)C.擔(dān)輪幼蟲(chóng)D.浮浪幼蟲(chóng)
A.不對(duì)稱B.輻射對(duì)稱C.兩側(cè)對(duì)稱D.螺旋形