http://www.ego4u.com/en/cram-up/grammar/conditional-sentences/type-2/exercises
http://www.perfect-english-grammar.com/second-conditional-exercise-1.html
http://www.englisch-hilfen.de/en/exercises/if_clauses/type_2_statements.htm
http://www.englisch-hilfen.de/en/exercises/if_clauses/type_2_negation.htm
http://www.englishgrammarsecrets.com/secondconditional/exercise1.swf
http://web2.uvcs.uvic.ca/elc/studyzone/410/grammar/2cond1.htm
http://www.nspeak.com/newbasic/grammatica/ipoteticosecondo.htm
http://www.learnenglishfeelgood.com/grammar-secondconditional1.html