单项选择题
A.103拷贝/ml B.104拷贝/ml C.102拷贝/ml D.105拷贝/ml
A.Friderick Griffith B.Alfred Hershey C.Martha Chase D.Oswald Avery
A.核苷的结构 B.磷酸二酯键 C.碱基顺序 D.核苷酸的结构