相关推荐： 托福阅读tpo26第二篇 托福official02passage2阅读真题
托福TPO作为大家托福备考的模考工具，它的题目对我们有很大的参考价值，为了帮助大家备考，下面小编给大家带来托福TPO2Part2阅读原文及参考答案，望喜欢。
托福TPO2Part2阅读原文
The Origins Of Cetaceans
It should be obvious that cetaceans-whales, porpoises, and dolphins-are mammals. They breathe through lungs, not through gills, and give birth to live young. Their streamlined bodies, the absence of hind legs, and the presence of a fluke1 and blowhole2 cannot disguise their affinities with land dwelling mammals. However, unlike the cases of sea otters and pinnipeds (seals, sea lions, and walruses, whose limbs are functional both on land and at sea), it is not easy to envision what the first whales looked like. Extinct but already fully marine cetaceans are known from the fossil record. How was the gap between a walking mammal and a swimming whale bridged? Missing until recently were fossils clearly intermediate, or transitional, between land mammals and cetaceans.
请关闭浏览器的畅读模式或者取消屏蔽JavaScript的正常运行，避免出现内容显示不全或者段落错乱。
原网页地址：https://www.potelypower.com/xuexi/456517.html