PASADO PERFECTO VERBOS https://www.ego4u.com/en/cram-up/grammar/irregular-verbs http://conjugador.reverso.net/conjugacion-ingles-verbo-wring.html ---------------------------------------------- https://learnenglish.britishcouncil.org/en/quick-grammar/past-perfect http://blog.esllibrary.com/2013/12/12/past-perfect-vs-past-perfect-progressive/ -------------------------------------------------- - https://en.islcollective.com/resources/printables/worksheets_doc_docx/past_participle_verbs/present-perfect-verbs/39513 https://en.islcollective.com/resources/printables/worksheets_doc_docx/past_tenses/past-continuous-progressive/86571 http://www.cambridge.org/grammarandbeyond/wp-content/uploads/2012/09/Communicative_Activity_Hi-IntAdvanced-Past_Perfect.pdf https://en.islcollective.com/resources/printables/worksheets_doc_docx/past_simple_and_participles/participles-intermediate-b1/1871 https://en.islcollective.com/resources/printables/worksheets_doc_docx/irre