如图所示，一束光由空气斜射入玻璃砖，画出这束光经过玻璃砖两个面折射的光路．

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图是某家庭红绿色盲遗传图解．图中除深颜色代表的人为红绿色盲患者外，其他人的色觉都正常．正常色觉与红绿色盲是一对相对性状，由一对等位基因（B、b ）控制．据图回答问题．

（1）红绿色盲是由____ 染色体上基因控制的____遗传病．

（2）图中III₃的基因型是____ ，III₂的可能的基因型是____ ．

（3）IV₁是红绿色盲基因携带者的可能性是　____ 　．

上图表示9个5相加.

根据短文内容，选择正确答案。

    Peter always doesn't know the way. His friends often laugh at him. They say he needs a map to find the bathroom in his own house. In his eyes, every street looks the same, and he doesn't know which way to go. Sometimes he has to take a taxi home because he can't remember the way to his house.

    Peter watches a lot of films and reads a lot of books about animals. Each bird knows which way is south. Bats (蝙蝠) can fly at night and find their way with their ears. He feels embarrassed (困窘的) because all these animals have a good sense of direction. He tries to find his way with the help of stars in the sky. There is a star called the North Star, and he knows how to find it.     Of course, Peter's friends are still laughing at him, because he can only see the North Star outside when it is sunny at night. He can't tell the directions in the daytime or when he is inside or when it is cloudy.