When there is a form of "to be" in the sentence (am,are,is,was,were), you use that form at the
front of the sentence:
- She is a great tennis player -> Is she a great tennis player?
It is also possible to form a question using the WH-words:
What / Where / When / Who / Which / Why / Whose / How:
- Who is there? / What are you doing? / Why do we need to do this? /
- How are you doing?