人类的第一个朋友是忠诚的狗，它陪伴我们走过岁月和风雨。她电影m3u8高清在线观看

　　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?