Physical model building should be an abstract one which should be based on the concrete conditions, discard the dross and select the essential, seize the principal contradiction and conform to the knowledge law.

• 物理模型的建立,应根据具体条件,去粗存精,抓住主要矛盾,建立起抽象化的物理模型,使之符合人类的认识规律。