THEORY
ENGLISH
SPANISH
REMEMBER SENTENCES STRUCTURE
THEORY & PRACTICE
http://www.englishgrammarsecrets.com/presentperfect/menu.php
http://www.curso-ingles.com/aprender/cursos/nivel-avanzado/verb-tenses-present-perfect/present-perfect
http://www.curso-ingles.com/practicar/ejercicios/present-perfect
http://www.agendaweb.org/verbs/present_perfect-exercises.html
EXPRESSIONS