1. I help my mum in the garden
Who helps your mum in the garden?
Whom do you help in the garden?
Where do you help your mum?
You help my mum in the garden, don't you?
Do you help your mum in the garden or in the kitchen?
2. We are helping our mum in the garden?
Who is helping your mum in the garden?
Whom are you helping in the garden?
Where are you helping your mum?
Your are helping our mum in the garden, aren't you?
Are you helping your mum in the garden or in the store?
С точки зрения здравого смысла это все вопросы.