人类第一个朋友
He has shared our lives for 20,000 years. Along the way, he has helped us find food, kept our livestock, protected us from our enemies, guided us in extreme conditions, and saved us from peril. Now, he comforts us, relieving loneliness and helping us cope with old age. How did dogs come about?

切换线路
遇播放卡顿或无法播放时,可切换线路播放