"I do not know my teacher's name."
Translation:저는 제 선생님 성함을 몰라요.
*Where is the subject?
When the subject (or any other sentence component) is well implied in the context, you may freely drop it in Korean, though you will mostly see and be asked to submit full sentences here since translation exercises do not come with any context. If you come across an incomplete sentence in this course, then the dropped component is probably people in general (often translated to one or you), or something very obvious even without context.