This excercise is best done with a tape that you can pause and rewind. You can tape a television show, a commerical or put in a movie. Turn the sound to OFF.
Watch for 5-10 minutes with your finger on the pause button. Watch, pause, then fill in the dialog on your own. If it is something you've seen before, try not to recreate what you think they said but come up with something new.
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