读中学时,在一堂生物课上,老师问我们:“树什么地方最硬?”“树结。”我们回答说。老师满意地点了点头,然后又问:“树什么地方最容易折断呢?”老师见我们回答不上来,便替我们回答说:“也是树结。”也是树结?最硬的地方怎幺最容易折断呢?老师解释说: “暴风雨过后,你拣起一些折断的树枝看一看,就会发现,大多数树枝折断的地方,正是有节的地方。” When I was in high school, in a biology class, the teacher asked us, “Where is the tree the hardest?” “Tree.” We answered. The teacher nodded with satisfaction, and then asked: “Where is the tree most likely to break?” When the teacher said we could not answer, he answered us, “It is also a tree.” And what is the hardest place? Easy to break off? The teacher explained: “After the storm, you pick up some broken branches and take a look, you will find that most of the broken branches where it is precisely the festival.”