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12 they have known him for many years. 3 The children have been watching cartoons for 2 hours. 4 We haven't had a holiday for 5 years. 5 She has been teaching at this school for twenty years.6 Mary and Sue have been collecting stamps for four hours. 2I have been reading Tolstoy stories in the park for two hours. I have read three stories. Granny has been knitting in the living room since morning. Helen has been traveling round Europe for 3 week.She has already visited 3 countries.