Text type: an invitation How to write a formal invitation http://www.wikihow.com/Write-a-Formal-Invitation How to write and invitation email / letter http://tuoitrenews.vn/english-study/4117/how-to-write-an-invitation-emailletter Writing invitations and responding http://www.english-at-home.com/business/responding-to-written-invitations/
Writing skill: spelling verb endings Grammar notes http://www.oxforddictionaries.com/words/verb-tenses-adding-ed-and-ing Spelling rules por –ed forms http://www.myenglishpages.com/site_php_files/grammar-lesson-spelling-ed-forms.php Spelling rules –ing form http://www.grammar.cl/Notes/Spelling_ING.htm Spelling rules present simple http://www.perfect-english-grammar.com/present-simple-spelling.html