Dave Green is a 12-year-old boy. He lives in Shanghai with his grandparents, parents and sister Cindy. Dave likes blue best.Look,his jacket and backpack are blue.He is in Class 3.22 boys and 18 girls are in his class.His good friends Liu Kun and Li Jie are in Class 3,too.Miss Wang is their science teacher.She is a good teacher. Her classes are fun. They all like her a lot. Science is not difficult for them! Dave likes playing computer games,but he doesn't play them every day. He studies science every day.

我国淡水渔业最发达的地区是（　　）

美国阿拉斯加的费尔班克斯素有“北极光之都”之称，其观赏极光的最佳季节是（   ）

雄鸡为ZZ，雌鸡为ZW，缺少染色体Z会致死。环境的影响使一只ZW的小鸡发育成能正常交配的公鸡，该公鸡与正常母鸡交配,后代性别为（    ）