Longitudinal study ; Dual language acquisition; Bimodal language acquisition; Spracherwerb (biling.) ; Language acquisition (biling.) ; Bilingual language acquisition ; Second language acquisition in children; Kindlicher Zweitspracherwerb; Child second language acquisition ; Logische Partikel; Konjunktion (Logik) ; Conjunction (logic) ; Connective ; Text production ; German ; Turkish