What is Geoffrey Chaucer's contribution to English language

Geoffrey Chaucer,the founder of English poetry,was born,about 1340,in London。Chaucer's contribution to English poetry lies chiefly in the fact that he introduced from France the rhymed stanzas of various types,especially the rhymed couplet of iambic pentametre(to be called later the "heroic couplet"to English poetry,instead of the old Anglo-Saxon alliterative verse。Though drawing influences from French,Italian and Latin models,he is the first great poet who wrote in the current English language。His production of so much excellent poetry was an important factor in establishing English as the literary language of the country。The spoken English of the time consisted of several dialects,and Chaucer did much in making the dialect of London the foundation for modern English speech。