Teacher:We all know that beat causes an object to expand an cold cauese it
to contract. Now,can anyone give me a good example?
John:Well ,in the summer the days are long,and in the winter the days are short.
老师:我们都知道热胀冷缩的道理。现在,谁给我举个例子?
约翰:嗯,在夏天天都长,在冬天天都短。