The best time to plant a tree was 20 years ago; the second best time is now.
种一棵树最好的时间是20年前,第二好的时间是现在。
Sometimes the simplest melodies carry the deepest emotions.
最好的领导者是那些多听少说,并向周围每个人学习的人。
历史学家必须是诗人,不是为了创造,而是为了重新创造。
农业科学家的责任就是让土地多产粮食,让农民多收粮食。
Reinforcement is the central factor in the acquisition of new behavior patterns.