cetaceans什么意思解释

Cetaceans reduce the number of breaths they take during rest periods.鲸类动物在休息时减少它们的呼吸次数.It is not clear whether cetaceans undergo dream sleep.鲸类动物是否经历梦睡眠还不清楚.Missing until recently were fossils clearly intermediate, or tr...

cetaceans的音标：...