人的皮肤颜色由基因A和a控制，正常肤色由显性基因A控制，白化肤色由隐性基因a控制。一对肤色正常的夫妇生了一个肤色白化的男孩，则男孩父亲的基因组成是：

关于粒子和宇宙，下列说法正确的是：（  ）

已知X原子的质量为2.657×10^-26kg，碳-12原子的质量为1.993×10^-26kg．则X原子的相对原子质量是____。X原子的名称是____。

    My cousin Sandy is1English girl. Her2name is White. She is 12. The girl is3. In her room, her books and tape player4in the bookcase. Her pencil box is on the5. Her ruler is on the desk, too. And a set 6 keys are in her pencil box. A baseball is under the desk,7 it's not Sandy's. It's her brother8. Sandy has a computer. 9 on the table. There is a photo on the wall. Two girls are in the photo. Do you know10the two girls are? Well, they are Sandy's good friends, Mary and Anna.