题目

My school is not big but beautiful. There is a garden in the school. There are many flowers in the garden. The flowers are colorful-there are all kinds of colours. In the center(中心) of the garden, there is a pool. The fish are swimming in it. They look very happy and free.There are two teaching buildings around the garden. There are 18 classrooms in it. And there are also many other rooms in it-music room, reading room, language lab and library. There are all kinds of books in the library, such as storybooks, cartoon books and magazines. You can read them after class.The playground is behi科学家发现睾丸决定基因是人睾丸发育的必要条件，人睾丸决定基因一般位于Y染色体上，当含该基因的一段Y染色体易位到其它染色体上，人群中会出现性染色体组型为XX的男性（每20000名男子中有一个）。下列为某家系患某种伴性遗传病的遗传图谱，请分析回答： （1）该遗传病位于___▲___染色体上，属于___▲___遗传。 （2）6号个体的睾丸决定基因可能位于___▲___染色体上。 （3）若不考虑基因突变，请解释6号个体不患该伴性遗传病的原因___▲___。 （4）7号个体和8号个体再生一个患该伴性遗传病女孩的几率是___▲___，请用遗传图解表示: