有些名词为单数形式，但做整体概念来看待，称为集合名词或集体名词，如：people police cattle，其谓语动词一般用复数。有些名词为单数形式，做整体概念来看待时，谓语动词用单数。强调整体中具体人或事物时，谓语动词用复数。如：class, family, audience, committee, army.
【例句】
1) The class are doing experiments on heat and light in the lab.
2) A large class is like a big banquet, which requires a teacher to make full pr eparation and have good performance.