Category (theory of grammar) ; Erstspracherwerb; First language acquisition; Ontogenese; Language acquisition ; Syntactic development; Morphological development; Morphologie (Spracherwerb) ; Syntax (Spracherwerb) ; Grammatical development ; Inhaltswort; Content word; Open class word; Closed class word; Function word/Content word ; Conjugation; Verb inflection ; Null subject; pro-drop; Subjectless clause ; English ; French ; Spanish
