English as a second language; ESL; TESOL ; GERS; CEFR; Quadro Comune Europeo di Riferimento; Common European Framework of Reference for Languages ; LLC ; Lexikometrie; Lexicometry; Automated Similarity Judgment Program; ASJP; Lexicostatistics ; Validity (method.) ; Evaluation criterion (method.) ; Lexical choice ; Zweitspracherwerb (Textproduktion) ; Second language acquisition (text production) ; Text production (second language acquisition) ; Zweitspracherwerb (lex.) ; Second language acquisition (lex.) ; Vocabulary (second language acquisition) ; Colligation; Collocation ; Evaluation criterion (text.) ; English