1. Why isn't Ann cooking dinner? - She's already cooked it.
2. Why don't boys learn a song? - The boys have already learned a song.
3. Why don't you help us? - You've already helped us.
4. Why doesn't he watch the movie? - He's already watched it.
5. Why don't they learn verbs? - They've already learned verbs.
6. Why aren't you studying for exams? - I've already studied for exams.
7. Why doesn't he answer this question? - He's already answered this question.
8. Why don't they print documents? - They've already printed the documents.