题目

    I will never forget the day--- September 10th 2009, when my class went on a field trip to the beach and I had so much fun. When we returned to school, my teacher told me to go to the headmaster’s office. When I got into the office, I saw a police officer. Suddenly, I realized something was wrong. The police officer told me what had happened and we went to pick my sister up. After that, we went to the hospital and waited. Time went slowly. Finally, we got to see our mother. It was terrible. On the next day, the headmaster came and told my two teachers what had happened. I was t下图是某夫妇体细胞染色体组成示意图，请回答:（1）染色体的主要组成成分是 和 。（2）从染色体的形态和组成看，图甲表示 （填“男”或“女”）性体细胞染色体组成。（3）理论上推算，这对夫妇生一个孩子是女孩的可能性为 。（4）若该对夫妇中，丈夫有耳垂（Dd），妻子无耳垂（dd），他们生了一个有耳垂的孩子，该孩子的基因组成是 。