我们感受到的每一种感觉都是复杂分子机制的结果。
距离不仅仅是一个物理概念,还是一个社会和经济概念。
在贫困社区,希望是一种稀缺资源。
Books are the quietest and most constant of friends; they are the most accessible and wisest of counselors, and the most patient of teachers.