I don't know if this would be covered later if it is the case, but is there a difference between "to think" as in have an opinion about something and "to think" as in to believe, and also to be thinking about smething? (for example "I think it isn't beautiful" as an opinion as you can see it, "I think it won't beautiful" as in you haven't seen it yet, but think that when you do, what you see won't be beautiful and "I think about it", or for those who know Danish, the difference between "at synes" and "at tro" and "at tænke")

I get skirt and dress mixed up every time...

This should be said to your significant other when they are wearing a nice skirt and the skirt of the other person is not as good as what they are wearing. +

I think, that skirt is not beautiful.---What's wrong with this sentence?