size fractionation的用法和样例：
例句
- A step in the right direction, Wenzel says, would be defining the vehicle classes by size rather than weight.
温契尔表示，正确的方向应该是依据体积而非重量订定汽车分级。 - In order to evaluate the classification efficiency of a classifier, this paper introduces the concepts of classification cut size and collection cut size.
为了评价分级机的分级效果，本文引入了分级粒径和收集粒径的概念。
