Hi! Here you have some links to practise "going to" future sentences.
Come on, It's very easy!!!
http://www.englishexercises.org/makeagame/viewgame.asp?id=5640
http://www.ego4u.com/en/cram-up/grammar/future-1-going-to/exercises
http://www.ego4u.com/en/cram-up/grammar/future-1-going-to
http://www.englisch-hilfen.de/en/exercises/tenses/going_to_future_statements.htm
http://saberingles.com.ar/curso/lesson11/05.html
