dozen用作名词时表示十二个，很多，许多等含义；用作形容词，表示一打的，十二个的。dozen可用作量词, a dozen of修饰名词时of可省略,但dozens of中的of不能省去。
1. 与具体数字连用时，不加复数词尾 –s；若后接名词，通常也无需用介词of。如：
He bought three dozen bottles of wine.他买了36瓶酒。
He has lived here for two score years. 他已在这儿住了40年。
2.偶尔也可见到受具体数字修饰的dozen, score后接 of，但惯用法认为省略 of则常见。
3. dozen可用作量词, a dozen of修饰名词时of可省略,但dozens of中的of不能省去。
There were dozens of people there. 那里有许多人。
I have heard of that scores of times. 那件事我已听过很多遍了。
4. 当与a few, several, many等数目不很具体的词连用时，带不带复数词尾 -s均可，但是注意：若不带复数词-s，其后的介词of可以省略；若带复数词尾-s，则其后介词of不能省略。
several dozen(s) of eggs=several dozen eggs 几打鸡蛋
several dozen (of) pencils= several dozens of pencils 几打铅笔
5. 若其后的名词受the, these, those等特指限定词的修饰，或其后接的是us, them 这样的人称代词时，则此时必须用介词of。如：
I had bred a dozen of chickens.
我饲养了12只小鸡。
There were about a dozen of them.
大约有十二人。
6.用作形容词，表示一打的，十二个的。
My mother bought a dozen eggs.
我妈妈买了一打鸡蛋。
They began by baking two dozen loaves.
他们通过烘烤两打的面包开始。
