Ошибки. 1. hans is businessman. 2. you family is very nice. 3. i like listen to music. 4. our school has a lot of students. 5. they were fishing when hans was falling into the water. 6. it rained when we went out. 7. we were dancing at the disco when we saw sandy. 8. i was losing my money when i bought presents. 9. i broken my leg while i was skiing.10. they are sitting in the garden when it started to rain.

1. Hans is a businessman. 2. Your family is very nice. 3. I like to listen (listening) to music. 4. Our school has got a lot of students. (Хотя здесь можно оставить и так) 5. They were fishing when Hans fell into the water. 6. It was raining when we went out. 7. We were dancing at the disco when saw Sandy. 8. I lost my money when I was buying presents. 9. I broke my leg while I was skiing. 10. They were sitting in the garden when it started ti rain.
Я думаю так, у кого есть поправки, с радостью посмотрю