Link de ejercicios con estructuras gramaticales y tiempos verbales
http://www.really-learn-english.com/examples-of-past-progressive-tense-es.html
http://www.really-learn-english.com/examples-of-simple-present-tense-es.html
http://www.really-learn-english.com/examples-of-simple-past-tense-es.html
http://www.really-learn-english.com/examples-of-simple-future-tense-es.html
http://www.really-learn-english.com/examples-of-present-progressive-tense-es.html
http://www.really-learn-english.com/examples-of-future-progressive-tense-es.html
http://www.really-learn-english.com/examples-of-present-perfect-tense-es.html
http://www.really-learn-english.com/examples-of-past-perfect-tense-es.htm
http://www.really-learn-english.com/examples-of-future-perfect-tense-es.html
http://www.really-learn-english.com/examples-of-present-perfect-progressive-tense-es.html
http://www.really-learn-english.com/examples-of-past-perfect-progressive-tense-es.html
http://www.really-learn-english.com/examples-of-future-perfect-progressive-tense-es.html