本集内容. Dogs were man's best friend far earlier than thought. 狗成为人类 “最佳伙伴” 的时间远早于早前认知. 文字稿. It's a small piece of jawbone, bu ...

The effects of pollution on London's schoolchildren 空气污染对伦敦中小学生的影响 Episode 181122 / 22 Nov 2018 Learn English words and ...