题目

听下面一段较长对话，回答以下小题。【1】When is Sherry’s birthday?A. Tomorrow. B. The day after tomorrow. C. The day before yesterday.【2】What will the man and the woman buy for Sherry?A. Some flowers. B. A record. C. Some chocolates. 答案：【答案】【1】A【2】B【解析】此题为听力题，解析略。【1】此题为听力题，解析略。【2】此题为听力题，解析略。10000个基因型为AaBb的卵原细胞，假设符合自由组合定律的话，理论上可形成Ab基因型的卵细胞数为(　　) A．2500个    B．5000个   C．7500个  D．10000个