Questions & Answers about Plomba je u zubu.
- plomba = filling (the dental filling)
- je = is
- u = in
- zubu = tooth in the form required after u
So the sentence is literally Filling is in tooth, which in natural English is The filling is in the tooth.
Je is the 3rd person singular form of the verb biti (to be), meaning is.
So:
- Plomba = the subject
- je = is
- u zubu = location phrase, in the tooth
Serbian usually does use a form of to be in sentences like this, just as English does:
- On je ovde. = He is here.
- Knjiga je na stolu. = The book is on the table.