PTE Academic ; Composition (teaching of) ; ESP; English for academic purposes; EAP ; Error analysis (language teaching) ; GERS; CEFR; Quadro Comune Europeo di Riferimento; Common European Framework of Reference for Languages ; Sampling; Language corpus; Sprachkorpus; Datensammlung; Data collection; Textkorpus (method.) ; Text corpus (method.) ; Corpus linguistics ; ICLE ; PICAE ; Academic language; Scientific language ; Techniques (in research) ; Research techniques ; Zweitspracherwerb (Textproduktion) ; Second language acquisition (text production) ; Text production (second language acquisition) ; Evaluation criterion (text.) ; Sachtext; Scientific article; Sachbuch; Nonfiction; Technical discourse ; English