实例一：假肥大性肌营养不良，患者几乎全部为男性，在成年前因所有肌肉纤维坏死而死亡，无生育能力。致病基因是位于X染色体上的隐性基因。

实例二：鸡的性别决定方式是ZW型（♀ZW、♂ZZ）。鸡的芦花（A）与非芦花（a）由位于Z染色体上的基因决定。

阅读短文，回答问题。

    Hello. I'm Peter. I'm a pupil. I go to school and study the boring knowledge(知识) every day now. I hope our school will change in the future. Schools will be different then. They will be under the sea, on high mountains and even in space. Robots will help us find books in the library and do our homework at home. We will use computers in all our lessons. They will help us see dinosaurs and other interesting things. We will have lessons with students from other countries. We will do a lot of things online together. We won't carry books to school. All our books will be on a small computer.