Mr. and Mrs. Brown lived in a small town near London with their children. Sometimes Mr. Brown came back home from work very late, when his wife and the children were asleep, and then he opened the front door of this house with his key and came in very quietly. But one night when he was coming home very late, he lost his key, so when he reached his house, he rang the bell. Nothing happened. He rang it again. Again nothing happened. Nobody moved inside the house. Mr. Brown knocked at(敲)the bedroom window, he spoke to his wife, he shouted, but she didn't wake up. At last he stopped and thought for a moment. Then he began to speak like a small child. "Mother! "he said. "I want to go to the toilet!" He spoke quite quietly but at once Mrs. Brown woke up. Then he spoke to her, and she opened the door for him.

“故”字共____笔，偏旁是____，组词____。

⑴f（x）在m，n上是单调的；

⑵当定义域是m，n时，f（x）的值域也是m，n，则称m，n是该函数的“和谐区间”．若函数f（x）= $\frac{a+1}{a}$ ﹣ $\frac{1}{x}$ （a＞0）存在“和谐区间”，则实数a的取值范围是____．