片语
index of difficulty难度指数
Difficulty And Differentiation Index难度区分度
difficulty index of caving垮冒难度指数
item difficulty index试题难度指数
Difficulty index for apple难易度指数
Weaving Difficulty Index织造难度系数
task difficulty index任务难度指数
index difficulty weighting指标难度赋权法
operative difficulty index操作难度