“酒是陈的香”，其原因之一是酒在储存过程中生成了具有香味的乙酸乙酯，在实验室我们也可以用如图所示的装罝制取乙酸乙酯．
①两个钝角相等；
②等式两边加上同一个数或同一个整式，所得的结果仍是等式；
③今天天气很晴朗啊；
④三角形的内角和是180°．
It was this exploring around problems and his ____(充满活力的) spirit that led to his most famous invention—the telephone in 1876.
根据下面提供的图文信息，简要写出其蕴含的物理知识．
甲：____ ；乙：____ ；丙：____ ．
I began to work in Beijing in the year New China was founded.
