He is here. → Is he here?

I am crazy. → Am I crazy?

He can play guitar. → Can he play guitar?

You must go now. → Must you go now?

I should stop. → Should I stop?

They are French. → Are they French?

There is a car. → Is there a car?

There are errors. → Are there errors?

The film has started. → Has the film started?

John had eaten. → Had John eaten?