English as a second language; ESL; TESOL ; Worthäufigkeit; Häufigkeitsliste; Frequency list; Frequency (lex.) ; Word frequency ; Frequency (pragm.) ; Discourse analysis (pragm.) ; Diskursgrammatik; Gesprächsanalyse; Konversationsgrammatik; Conversational analysis (pragm.) ; English as international medium ; Second language acquisition (pragm.) ; Zweitspracherwerb (pragm.) ; Interactionist hypothesis (second language acquisition) ; Conversational analysis (second language acquisition) ; Lemmata ; English