police是集合名词，表示警察(泛指)，本身具有复数含义。(就和people一样)

policeman 警察 复数policemen

policewoman 女警 复数policewomen

相关介绍

The two policemen were joined by another policeman also carrying a pistol.

另一名持枪警察和那两名警察会合了。

There were 2,250 policemen on duty in and around the stadium

在体育场内及周边有2,250名警察在值勤。

Policemen and policewomen work at a police station.

男女警员在警察局工作。

Two policewomen are directing traffic at the crossing.

两名警花在十字路口指挥交通。