基于词汇密度的教材难易度比较研究——以毛立群《物流专业英语》和牛国崎《物流专业英语》为例
A Comparative Study on the Difficulty of Textbook Based on the Lexical Density—Taking Mao Liqun’s Professional English for Logistics and Niu Guoqi’s Professional English for Logistics as Examples

教材难易度是教材编写的重要原则，也是衡量学生学习质量的重要依据。词汇密度能侧面反映出不同教材的难易度，反映教材的变化特征：词汇密度越大，教材难易度越高，反之亦然。本研究利用Ure和Halliday的词汇密度计算公式，分别计算毛立群《物流专业英语》和牛国崎《物流专业英语》两本教材的词汇密度，从而推测出教材的难易度变化。本研究旨在通过词汇密度研究教材难易度，为教材的合理编排提供一定的参考意义。
The difficulty of textbook is not only an important principle of compiling teaching materials, but also an important basis to measure students’ learning quality. Lexical density can reflect the difficulty of different textbooks and the changing characteristics of textbooks: the greater the lexical density, the higher the difficulty of textbooks, and vice versa. This study uses the lexical density calculation formula of Ure and Halliday to calculate the lexical density of Mao Liqun’s Professional English for Logistics and Niu Guoqi’s Professional English for Logistics respectively, so as to infer the change of the difficulty of the textbook. This study aims to study the difficulty of textbooks through lexical density, so as to provide some reference for the rational arrangement of teaching materials.