购买旧书,它们的词与新词相同,也可以去图书馆。
By used books. They have the same words as the new ones. Also libraries.
The most important skill in mathematics is the ability to think clearly.
我不睡觉,因为我太忙于梦想。
衡量一个领导者的真正标准不是他们有多少追随者,而是他们培养了多少领导者。