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http://www.perfect-english-grammar.com/past-perfect-exercise-1.html
http://www.montsemorales.com/gramatica/PastPerfect1.htm
http://www.english-grammar-lessons.com/pastperfect/exercise1.swf
http://www.englishgrammarsecrets.com/pastperfect/exercise2.swf
http://www.english-grammar-lessons.com/pastperfect/exercise2.swf