Dobar vecher vil
I'm not a teacher!
1. I think that a box may be covered with iron. /you mean fixed sheet metal fitting or some decoration made of iron?/
2. "furniture" is plural /only/, so if you need singular, it ought to be "piece or item of furniture" or you may to name it, eg: bed, sofa.
So, I propose: the sofa was covered with a chintz. /not pottery/
3. In the third sentence I would use 'with' too.
I think that some teacher or another person, much better then I, will help you.
If not, fifty percent of something is better than one hundred of nothing.
But, a half true is a whole lie!
Thank you for your question and,
Student or Learner