To be aware of the idea of social structure and to use it with sensibility is to be capable of tracing such linkages among a great variety of milieux.

对粗鲁的陌生人回以极度礼貌，很刺激。

数学的进步不仅仅依靠个人的努力，而是通过几代人的集体工作。

最好的肥料？是农民田间的足迹。