What is the difference with the correct answer and "Ty jsou nove veci"
Ty jsou nové věci. is incorrect. You have to use To jsou nové věci.
That's exactly what I thought. But at the top of my screen right now, the translation for the English sentence "Those are new things" is "Ty veci jsou nove" and that looked wrong so I asked.
Ty věci jsou nové was accepted for me
when do you use ty and when do you use to for those