Second language acquisition (language teaching) ; Zweitspracherwerb (Unterricht) ; Foreign language teaching ; Grammatizität; Grammaticalness ; Sprachbewahrung; Ethnolinguistic vitality; Vitality, ethnolinguistic; Sprachwechsel; Language shift; Heritage language; Language maintenance ; Processability theory; Language comprehension (second language acquisition) ; Subjunctive ; Volitiv; Volitive; Dynamische Modalität; Dynamic modality; Deontic modality ; English (American) ; USA (English language in the) ; USA (engl. Sprache in den) ; English in the USA; Englisch in den USA; American English ; Chicano; Puertoricans; USA (span. Sprache in den) ; Mexican American Spanish; USA (Spanish language in the) ; Spanglish; Inglañol; Tex-Mex; Spanish in the USA