下列物质中，既能与水反应，又能与盐酸反应的是（   ）

光明小学四年级2班部分学生体育课上做仰卧起坐情况如下表：

用计算器计算四年级2班部分同学平均仰卧起坐的个数

阅读下面材料，在空白处填入适当的内容或括号内单词的正确形式。

    There are all kinds of festivals throughout the world. Festivals are held____ (satisfy) and please the ancestors, to honor some famous people or important____(event), and to express people's gratitude to the God for bringing them a year of plenty. For example, in India, October 2 is ____national festival to honor  Mahandas Gandhi, the leader____helped gain India's ____(depend) from Britain.____ (tradition), in China the Spring Festival, which ____(celebrate) in January or February, is the most ____(energy) and important because it is a festival that looks forward____the coming of spring. Why are all these festivals everywhere? Because during the festivals, people can get together to eat, drink and have fun with each other,____ (forget) all the daily struggle and demands for a while.

从n($n\in N^{*}$,且n≥2)人中选两人排A，B两个位置，若其中A位置不排甲的排法数为25，则n=(    )