Learn Romanian: Fata este studenta. - The girl is the student.

In Romanian, you don't need to change the word order or add helping words to make a yes/no question. You just raise the pitch of your voice at the end of the sentence. So, Fata este studenta? is all you need to ask the question!

How would I use this sentence's structure to ask 'Who is the student?'

You would use the question word Cine (Who). Just replace Fata with Cine to get Cine este studenta? (Who is the student?).

Where is the word for 'the' in this sentence?

In Romanian, 'the' is attached to the end of the noun. The base words are fată (girl) and studentă (female student). To say 'the girl' and 'the student', that final sound changes to an 'a', giving us fata and studenta.

If the sentence was about a boy, how would the word for student change?

Because fata is feminine, we use the feminine word studenta. If the subject were masculine, like băiatul (the boy), the word for student must also be masculine. The base word is student, and 'the student' is studentul, making the sentence Băiatul este studentul.