1. 作数量词时，dozen十二个，score二十个。用法与hundred, thousand ...等类似。如：a dozen apples 十二个苹果(一打苹果)，two score chairs四十张椅子，three hundred people三百个人。

2. 作单位词时，score (二十) 后可接of，但dozen (一打)后接of很罕见。如：five score (of) fish一百尾鱼(省略of则score看作为数量词)，three dozen eggs 三打鸡蛋

3. 在表“几十个”不确定的泛指数时用dozens of或scores of，用法同tens of, hundreds of, thousands of…。如：dozens of / scores of students好几十个学生

4. dozens of和scores of前若用some, several, a few, many等词时，dozen和score可去掉“s”(很少保留)，同时也去掉of。如：several dozens/scores of people = several dozen/score people

5. 当后面有人称代词(you, us, them)时，名词前有定冠词(the)、物主代词(my, your, his, her, their, its)以及指示代词(these, those)限定时，要用“数词+dozen/score +of”，dozen和score均不加“s”。如：a dozen of them, two score of the books, three score of my sheep, four dozen of those children

6. 有三个惯用短语需特别记忆：three score (years) and ten 七十岁，古稀之年；three score of people 六十人；three score and ten people七十人