你知道吗,最早的闹钟是用大炮声音来报时的。在古代欧洲,曾出现过一种“太阳闹钟”。它是在大炮引火线上方安置一面凸透镜,太阳光透过凸透镜汇聚到一点,而引燃导火索。每天的特定时刻,太阳光的焦点刚好投射在导火线上,于是,大炮轰鸣,向人们报告时间。这闹钟可真够闹的呀!闹钟,? Did you know that the earliest alarm clock was to use the cannon sound to tell the time. In ancient Europe, there has been a “sun alarm clock.” It is a convex lens placed above the cannon’s firing line. Sunlight converges to a point through the convex lens, which ignites the fuse. At specific moments of the day, the focus of the sun is just on the fuse, so the cannon roars and reports time to people. This alarm clock is really alarming! Alarm clock,?