已知正项数列{a_n}的前n项和为S_n，且 $\sqrt{S_n}$ 是1与a_n的等差中项．

（Ⅰ）求数列{a_n}的通项公式；

（Ⅱ）设T_n为数列{ $\frac{2}{a_n{a}_{a+1}}$ }的前n项和，证明： $\frac{2}{3}$ ＜T_n＜1（n∈N^*）

    I like school days. I can learn many things from school. We have four classes in the morning and two in the afternoon. I like weekends, too. We don't go to school on Saturdays and Sundays. I often play ping-pong and play basketball on Saturday morning. I often play the violin (小提琴) on Saturday afternoon. I often do homework and play football on Sunday morning. I often go to the park on Sunday afternoon.

阅读材料，回答问题。

材料：

（1）图一中两大军事集团较量后的结果最终形成了怎样的世界政治格局？这一格局是怎样被打破的？
（2）图二、图三分别代表哪一军事同盟？
（3）第二次世界大战中有哪些重大军事行动体现了图三《联合国家宣言》的精神？分析此宣言对二战的进程产生了什么影响？
（4）由图四、图五可以看出，战后德日两国对战争态度存在什么不同？给我们哪些启示？