One fine afternoon, I was walking along Fifth Street when I remembered that it was necessary to buy a pair of socks. Why I wished to buy only one pair was unimportant. I turned into the first sock shop that caught my eye. A boy clerk, who could not have been more than seventeen years old came forward. “What can I do for you, sir?” he said. “I wish to buy a pair of socks.” I replied.

    His eyes shone. There was a note of excitement in his voice. “Did you know that you had come into the finest place in the world to buy socks?” I had no idea of that, as my entrance had been accidental. “Come with me,” said the boy, eagerly. I followed him to the back of the shop, and he began to pull down box after box from the shelves, showing their contents（内装物）for my choice.

    “Hold on, lad,” I said, “I am going to buy only one pair!” “I know that,” said he, “but I want you to see how beautiful these are. Aren't they wonderful!” There was on his face an expression of seriousness and pride and delight as if he were showing me the secrets of his religion（宗教信仰）. I became far more interested in him than in the socks. I looked at him in surprise. “My friend,” said I, “if you can keep this up, if this is not merely from having a new job, if you can keep up this high spirit and excitement day after day, in ten years you will own every sock in the United States.”

（Ⅰ）若0＜α＜ $\frac{\pi }{2}$ ，且sinα= $\frac{\sqrt{2}}{2}$ ，求f（α）的值；

（Ⅱ）求函数f（x）的最小正周期及单调递增区间．

南宋和北宋相比，其政治特点的相同之处有(      )。
 ①与少数民族政权并立    ②皇帝重文轻武，靠议和苟安
 ③投降派占上风，主战派受排挤 ④被少数民族政权所灭

下列能体现民族精神的核心的说法有（   ）
①差之毫厘，谬以千里            ②天下兴亡，匹夫有责 
③位卑未敢忘忧国                ④苟利国家，不求富贵 

在探究凸透镜成像规律的实验中，我们发现（   ）