Second language acquisition (language teaching) ; Zweitspracherwerb (Unterricht) ; Foreign language teaching ; Neurolinguistics ; Critical period (language acquisition) ; Alter (Einfluss auf Spracherwerb) ; Age (influence on language acquisition) ; Age of acquisition; AoA; Sensitive period (language acquisition) ; Critical period (second language acquisition) ; Alter (Einfluss auf Zweitspracherwerb) ; Age (influence on second language acquisition) ; Ultimate attainment (second language acquisition) ; Near-native competence (second language acquisition) ; AoA; Age of acquisition (second language acquisition) ; Sensitive period (second language acquisition)