下列哪级显微镜镜头的组合，观察到的细胞数目最多？（  ）

	目镜	物镜
A	15×	10×
B	10×	10×
C	8×	40×
D	15×	40×

利用分层抽样的方法在学生总数为800的年级中抽取20名同学，其中女生人数为8人，则该年级男生人数为____．

党的十八大以来，以***同志为核心的党中央坚持以人民为中心的发展思想，高度重视促进社会公平正义，通过调整国民收入分配格局，着力解决收入分配差距较大的问题，使发展成果更多更公平惠及全体人民，朝着共同富裕的方向稳步前进。******用“蛋糕”打比喻，一方面强调要千方百计把“蛋糕”做大，以利于全国人民都能分得一份较大的“蛋糕”；另一方面强调要将已有的“蛋糕”公平合理地分配给每个社会成员，让他们有更多的获得感，收入水平和生活水平逐步提高，以更大的积极性去做大“蛋糕”。

运用所学经济生活道理，结合上述材料，回答：

新中国成立后，我国解决民族问题的基本政策是                           （    ）

    Many young people like playing football very much. In China we can often see children playing football on the playground. In China and England, people call British soccer football. They don't call it soccer.
    A British soccer ball is round. There are eleven players in a team. But an American football is not round. It's like an egg. They also have eleven players on the field in one team.
    American football is very popular（流行的）in the USA. Players can catch the ball with their hands. But in a British soccer team, only the goalkeeper（守门员）can pick up the ball with his hands.
    Playing ball games is good for you. It can make you happy and healthy.