4月27日下午,刮着5级左右的风。下班回家的路上,我突然看到挂在电线杆的铝线上的纸条,被风吹得左右不停地摆动,并发出“哗啦哗啦”的声音。正好,下周我就开始讲授《声音的产生》,我正为音叉少不能做分组实验而犯愁。看到这情形,我不禁笑了:真是踏破铁鞋无觅处,得来全不费功夫！晚上,我准备了一张纸条,用大拇指和食指夹着纸条的一端,放在嘴 On the afternoon of April 27, there was a wind of about 5 levels. On the way home from get off work, I suddenly saw the note hanging on the aluminum pole of the power pole that was blown around and kept swaying with a “rattling” sound. Just now, next week I started teaching “Sound Generation,” and I was anxious to make a group experiment with little tuning fork. See this situation, I can not help but laugh: really steal the iron shoes without seeking, have to do all effort! In the evening, I prepared a piece of paper, with the thumb and index finger holding the end of the note, on the mouth