1. 用作名词，是集合名词。作主语时，谓语用单数(视为整体)或复数(考虑其个体成员)均可。如：
The crowd moves on, and no one tries to stop it. 人群向前移动，谁也没试图阻止。
The crowd were running in all directions. 人群往四面八方跑去。
强调人数多时，可用复数形式。如：
There were crowds of people waiting to get in. 有许许多多的人在等着进去。
2. 用作动词，表示“聚集”、“挤满”，可用作及物或不及物动词。如：
Shoppers crowded the streets. 买东西的人挤满了大街。
He managed to crowd into the train. 他总算挤上了火车。
People crowded round to get a better view. 人们争相围观。
常用结构 be crowded with。如：
The hall was crowded with people. 大厅挤满了人。
The exhibition was crowded with visitors. 展览会挤满了参观的人。
3. 派生形容词 crowded 意为“拥挤的”。如：
crowded trains (hotels, roads, shops) 拥挤的火车(旅馆，道路，商店)
但是，汉语的“拥挤的交通”不能直译为 crowded traffice, 而是用 busy [heavy] traffic。