新东方在线网络课堂 六级 新东方在线 > 六级 > 英语六级听力 > 正文

2018年6月英语六级听力常考时文:Evolution and Wheels

2018-04-16 15:58:07 来源:网络六级资料下载

英语六级资料大全下载英语六级资料大全下载

六级关注: 六级词汇看图记忆汇总 六级听力常考考点汇总 六级阅读常见词组汇总

六级必过: 2018年12月英语六级听力口语关键句汇总 六级考试阅读必背词汇盘点

真题试卷: 2018年6月大学英语六级真题及答案大汇总 大学英语六级真题解析汇总

六级必过: 2018年6月英语六级真题答案解析大汇总 英语六级真题及答案下载汇总

  2018年6月英语六级听力常考时文盘点

  英语六级听力常考时文:Evolution and Wheels

  1.What connects the living cells to the heart in an animal's body? ...

  2.What is crucial to a wheel? ...

  3.What is the feature of cats' claws? ...

  In the past, evolutionary biologists contemplating the absence of wheels in nature agreed that the explanation was not undesirability: wheels would be good for animals, just as they are for us. Animals were prevented from evolving wheels, the biologists reasoned, by the following dilemma: living cells in an animal's body are connected to the heart by blood vessels, and to the brain by nerves. Because a rotating joint is essential to a wheel, a wheel made of living cells would twist its artery vein and nerve connections at the first revolution, making living impracticable. However, there is a flaw in the argument that the evolution of wheeled animals was thwarted by the insoluble joint problem. The theory fails to explain why animals have not evolved wheels of dead tissue with no need for arteries and nerves. Countless animals, including us, bear external structures without blood supply or nerves - for example, our hair and fingernails, or the scales, claws, and ho rns of other animals. Why have rats not evolved bony wheels, similar to roller skates? Paws might be more useful than wheels in some situations, but cats' claws are retractable: why not retractable wheels? We thus arrive at the serious biological paradox flippantly termed the RRR dilemma: nature's failure to produce rats with retractable roller skates.

  2018年6月英语六级听力常考时文盘点

英语六级必备资料下载

2018年6月英语六级词汇完整版带音标下载

英语六级必备工具:测测你的词汇量能过六级吗

测测你的词汇量能过六级吗

本文关键字: 英语六级听力 六级听力备考

分享到:

课程试听换一换

相关推荐

四六级交流•下载

精品课限量免费领

今日特价课

六级实用•工具

六级课程排行榜本周本月

六级公开课更多>>

2018年6月六级写作真题解析-王兆飞 w 11分22秒
1 2018年6月六级写作真题解析-王兆飞
2018年6月六级阅读真题解析-舒洋 w 15分40秒
2 2018年6月六级阅读真题解析-舒洋
2018年6月六级听力真题解析-姚瑶 w 19分12秒
3 2018年6月六级听力真题解析-姚瑶
2018年6月英语六级听力真题音频mp3 w 29分13秒
4 2018年6月英语六级听力真题音频mp3
新东方在线老师唐迟解析2017年12月六级阅读真题 w 34分48秒
5 新东方在线老师唐迟解析2017年12月六级阅读真题

微博直播更多>>

推荐阅读