表示“警察”时，有时用 police，有时用 the police，两者的不同之处吗？
The police put a barrier across the road. 警察设了路障。
The police made three arrests yesterday. 警察昨天实行了3项逮捕行动。
Police immediately sealed off the streets. 警察立即封锁了街道。
Police blocked off the street after the explosion. 在发生爆炸之后，警方用路障封锁了那条路。
police 用作集合名词表示“警察部门”“警察机关”“警方”时，原来是要用定冠词。但在现代英语中，用不需要定冠词都可以。譬如下面两句均摘自柯林斯词典的 police 词条：
The police are also looking for a second car. 警方也在探寻另一辆车。
Police say they have arrested twenty people following the disturbances. 警方说骚乱发生后他们已逮捕了20人。
再如：
The police have every good reason to believe that he is guilty. 警方完全有理由认定他有罪。（剑桥词典）
The police seem certain they will find the people responsible for the attack. 警方好像确信他们会查出这起袭击事件的责任人。（剑桥词典）
Police are very careful when screening politicians’ bodyguards. 警方在挑选政要保镖时很小心。（朗文词典）
Police believe a lone gunman is responsible for the shooting. 警方觉得仅有一名持枪歹徒对此枪击事件负有责任。（麦克米伦词典）
