Are Some Dog Breeds Really Easier to Train? Not Really.
RJ Mackenzie，流行科学 选择狗不仅仅是审美问题。主人可能会喜欢柴犬厚厚的皮毛和狭窄的口鼻，但更欣赏它坚忍的天性和忠诚......
Why aren't mammals as colorful as reptiles, birds or fish?
许多哺乳动物的皮毛颜色为棕色和黑色。为什么它们不具有更奇特的颜色，例如紫色和霓虹粉色？
