Osmoregulation is a major function of kidneys and ( ) in fishes. A: skin B: rectal glands C: hepatic cecae D: gills E: fins

以下（ ）结构的存在增加了某些多毛类Annelida的气体交换面积。 A: 疣足鳃 (parapodial gills) B: 皮鳃 (dermal branchiae) C: 体环 (annuli) D: 横膈膜 (septa) E: 肠系膜 (mesenteries)