Syntactic development; Morphological development; Morphologie (Spracherwerb) ; Syntax (Spracherwerb) ; Grammatical development ; Critical period (language acquisition) ; Alter (Einfluss auf Spracherwerb) ; Age (influence on language acquisition) ; Age of acquisition; AoA; Sensitive period (language acquisition) ; Dual language acquisition; Bimodal language acquisition; Spracherwerb (biling.) ; Language acquisition (biling.) ; Bilingual language acquisition ; Coordinate bilingualism; Compound bilingualism; Dominanz (biling.) ; Dominance (biling.) ; Continuum (biling.) ; Second language acquisition in children; Kindlicher Zweitspracherwerb; Child second language acquisition