1 . The typical unipersonal verbs are: llover, nevar, tronar, helar, lloviznar, diluviar, granizar, relampaguear, amanecer, anochecer, and in general verbs referring to atmospheric fenomena. These verbs are used without subject, in third person of the singular or in infinitive.
Hoy llueve.
Mañana nevará.
Ayer estuvo diluviando.
These clauses have grammar impersonality, because it is not known who performs the action of the verb, but may not be considered impersonal.
2 Not typical unipersonal verbs
- In some cases, the verbs haber, ser and hacer follow this impersonal pattern: they do not have subject and are only used in the third persons of the singular or in infinitive.
Hace mucho frío.
Hay mucha miseria en el mundo.
Ya es muy tarde.
Hace tres minutos que ha llegado.
It is incorrect, therefore, the agreement of haber and hacer with the direct object in plural. The verb is always conjugated in third person of the singular.
Hubo muchos muertos en aquella batalla.
Ha habido inundaciones en el sur del país.
- Other not typical unipersonal verbs are: convenir, importar, parecer, pesar, bastar y poder. They may look like unipersonals, because are only conjugated in third persons of the singular and of the plural, but they do have subject.
Te conviene venir temprano.
Me parece que es viernes.
Puede que venga o puede que no.
Me basta que estés aquí.
Basta mirarte para saber que mientes.
Me pesa lo que le dije.