PRESENT PERFECT
http://www.ego4u.com/en/cram-up/grammar/present-perfect-simple
http://www.ego4u.com/en/cram-up/grammar/present-perfect-progressive
http://www.perfect-english-grammar.com/present-perfect.html
http://www.perfect-english-grammar.com/present-perfect-use.html
http://www.perfect-english-grammar.com/present-perfect-continuous.html
http://www.perfect-english-grammar.com/present-perfect-continuous-use.html
http://www.myenglishpages.com/site_php_files/grammar-lesson-present-perfect.php
http://www.myenglishpages.com/site_php_files/grammar-lesson-present-perfect-continuous.php
http://learnenglish.britishcouncil.org/en/english-grammar/verbs/present-tense/present-perfect
http://www.englishclub.com/grammar/verb-tenses_present-perfect.htm
http://www.englishclub.com/grammar/verb-tenses_present-perfect-continuous.htm
http://www.englishpage.com/verbpage/presentperfect.html
http://www.englishpage.com/verbpage/presentperfectcontinuous.html
http://www.ego4u.com/en/cram-up/grammar/present-perfect-progressive
http://www.perfect-english-grammar.com/present-perfect.html
http://www.perfect-english-grammar.com/present-perfect-use.html
http://www.perfect-english-grammar.com/present-perfect-continuous.html
http://www.perfect-english-grammar.com/present-perfect-continuous-use.html
http://www.myenglishpages.com/site_php_files/grammar-lesson-present-perfect.php
http://www.myenglishpages.com/site_php_files/grammar-lesson-present-perfect-continuous.php
http://learnenglish.britishcouncil.org/en/english-grammar/verbs/present-tense/present-perfect
http://www.englishclub.com/grammar/verb-tenses_present-perfect.htm
http://www.englishclub.com/grammar/verb-tenses_present-perfect-continuous.htm
http://www.englishpage.com/verbpage/presentperfect.html
http://www.englishpage.com/verbpage/presentperfectcontinuous.html