Erstspracherwerb; First language acquisition; Ontogenese; Language acquisition ; MLU; Mean length of utterance; Sentence length (child language) ; Kindersprache (pathol.) ; Child language (pathol.) ; Specific language impairment; SLI; Dysgrammatismus (Kindersprache) ; Dysgrammatism (child language) ; Handicapped language acquisition ; Inflection ; Spanish