In fact, they can only be used as verbs.They cant be referential pronouns.Verbs without definite subjects, auxiliary verbs and determination verbs are just some of their usages as static verbs.

• 实际上“有”“无”只能是同动字，不能是约指代字，无属动字、助动字和决辞只是同动字“有”“无”的用法归类。