"My aunt makes soup in winter."
Translation:Mijn tante maakt soep in de winter.
You don't have to always use an article with the seasons, e.g.:
- Het is winter/zomer/lente/herfst - not de winter/zomer/lente/herfst
But when you refer to the winter you do use an article e.g.:
- Morgen begint de winter/zomer/lente/herfst - not winter/zomer/lente/herfst
- Tijdens de zomer is het warm
I suppose you can look at it in a similar way as the times of day in English, e.g.:
- It is afternoon somewhere - but you don't say I make soup in afternoon it needs an article.
When you want to emphasise them, you can move them all the way to the front.
- Mijn tante maakt soms soep in de winter. (normal, no specific emphasis)
- In de winter maakt mijn tante soms soep. (emphasis on in de winter)
- Soms maakt mijn tante soep in de winter. (emphasis on soms)
With this particular sentence the problem is that it is linked to the English for Dutch speakers course. Technically speaking for the Dutch for English speakers course it should not be accepted, so please refrain from using it because in most other cases it won't be accepted.