The verb in a question also has a subject.The subject normally comes before the verb, but note:The subject is the naming part of a sentence. It appears before the verb to show: a) what the sentece is about; b) who or what performs the action. c) after the subject it comes the verb.
Here comes the train.
Rarely have I seen such a beautiful sight.
It could be argued that 'I' is the subject of the auxiliary verb BE - which is why we use 'am' rather than 'is' or 'are'.1) I was cooking. I = The subject of the verb COOK