分析以下实验：①比较电流做功的多少采用比较电灯发光的亮度；②研究电磁铁磁性的强弱比较能吸引铁屑的多少；③测滑动摩擦力的大小从匀速拉动的弹簧秤上读得；④在探究焦耳定律电流产生热量的多少时比较温度计示数变化的快慢。实验思想方法相同的是（）

    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.

下列是一个反映中国1903年一家四兄弟情况的历史故事，其中错误的一项是（    ）

电梯为居民上下楼带来很大的便利，出于安全考虑，电梯设置了超载自动报警系统，其工作原理如图所示，电梯厢底层装有压敏电阻R₁，R₂为保护电阻，K为动触点，A、B为静触点，当出现超载情况吋，电铃将发出报警声，电梯停止运行，下列说法正确的是（　　）