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　　Have you ever wondered what the world looks like through dogs' eyes, or whether dogs are color-blind(色盲的)？

　　We all know that humans' eyes see color u l cone cells(视锥细胞），and so do dogs'. But their cone cells aren't c 2 the same. Humans have three types of cone cells,which make us be able to see red. blue and green. Dogs have two types of cone cells that pick up blue and yellow. This m 3 that dogs see in a similar way to humans who have red-green color blindness.“Dogs can't see red or green and they see e 4 in blue and yellow,”says Jay Neitz, a professor at the University of Washington.

　　Humans may have the advantage in color vision(色觉)，but dogs have b 5 night vision than humans. This is b 6 dogs’ eyes have more light-gathering(聚光的)power than ours.

　　Dogs have t 7 seeing things up close. "Dogs can see things clearly if they're at l 8 13 to 20 inches away from their eyes,but if they are closer, they can't see them clearly," Sypniewski says. Humans can see things closer—about 10 inches away from the eyes. This fact about dogs might be unknown to most dog o 9 :If your dog recognizes(认出)you from a distance, it is not because of it seeing your face clearly 1 10 a human would,but rather because of your shape or the way you move.

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