A collective refers to a unified whole composed of a certain number of homogeneous individuals, and the individuals that make up the collective do not necessarily have all the attributes of the collective. The concept of a collective refers to the concept of using a collective as a reflective object. According to the above definitions, the following concepts shown in bold type are collective concepts:. ['Natural numbers are integers not less than 0.', 'People enjoy a wide range of democratic rights.', 'Our classmates come from all over the world.', 'Teachers are intellectuals.']