Teacher:We all know that heat causes an object to expand and cold causes it to contract. Now, can anyone give me a good example?
John:Well, in summer the days are long,and in winter the days are short.
老師:我們都知道熱脹冷縮的道理。現(xiàn)在,誰(shuí)給我舉個(gè)例子?
約翰:嗯,在夏天天都長(zhǎng),在冬天天都短。