可以理解为美国小学生的正经课外读物，不仅风靡米国，而且在全世界都是顶流作品。RAZ，就是Reading A-Z的缩写，出版方把所有读物按照A-Z的字母顺序来划分难度分级，读者可以按照这个顺序拾级而上，循序渐进地提高阅读能力。
A crow was sitting on a branch of a tree with a piece of cheese in her beak when a fox observed her and set his wits to work to discover some ways of getting the cheese. Coming and standing under the tree he looked up and said， “what a noble bird I see above me!
