should, must, have to

grammar
http://www.aulafacil.com/Ingejerc/Lecciones/Lecc26.htm
exercises
http://www.aulafacil.com/Ingejerc/Lecciones/Ejerc26.htm

http://www.englishexercises.org/makeagame/viewgame.asp?id=6270

http://www.englishexercises.org/makeagame/viewgame.asp?id=3401

prepositions: at, in, on

1. I usually go out weekends.
2. London is very cold winter but warm summer.
3. My sister works the hospital.
4. I will travel to New York June.
5. What are you doing Friday?
6. John and Mary got married 1989.

MORE EXERCISES:
http://www.saberingles.com.ar/exercises/indexm.html

opposite adjectives

1. cheap 
2. happy
3. new
4. fast
5. weak




a. old
b. slow
c. strong
d. expensive
e. sad

1. far
2. clean 
3. hot
4. early
5. thick




a. cold
b. thin
c. near
d. late
e. dirty

songs

http://www.saberingles.com.ar/songs/exercises/index1.html

present perfect & past simple

http://www.ego4u.com/en/cram-up/grammar/simpas-preper

http://www.aulafacil.com/Ingejerc/Lecciones/Lecc20.htm

http://www.englishpage.com/verbpage/verbs5.htm

http://www.curso-ingles.com/ejercicios-test-ingles/present-perfect-past-simple.php

present perfect grammar

http://www.curso-ingles.com/gramatica-inglesa/present-perfect.php
http://www.ego4u.com/en/cram-up/grammar/present-perfect-simple

http://personales.ya.com/mjandres/archivos/GRAMMAR4&5.PDF

http://www.englishpage.com/verbpage/presentperfect.html

comparative and superlatives

http://www.slideshare.net/guest1639c2/comparative-and-superlative-adjectives

http://www.tinyteflteacher.co.uk/learning-english/grammar/much-comparatives.html

http://www.tinyteflteacher.co.uk/learning-english/grammar/exercises/much-comparatives.html

http://www.perfectyourenglish.com/grammar/modifiers.htm