1 - inversion

A question is no more than a statement with a twist: simply switch Subject + Aux -> Aux + Subject
Bob is reading the paper. She has asked for more time. They will come tomorrow. She can play the piano. They don't know the answer.	Is Bob reading the paper? Has she asked for more time? Will they come tomorrow? Can she play the piano? Don't they know the answer?
And if there is no auxiliary: use the auxiliary DO
We like tea. They know the answer. She speaks Italian. Your dog barks a lot.	Do we like tea? Do they know the answer? Does she speak Italian? Does your dog bark a lot?

2 - tag

Add a tag to the statement and it becomes a question: Question = Statement + opposite Aux + Subject use a pronoun for the subject
Ben is talking to Ted. Mary has phoned Bob. They will come later. She can play the piano. Ted isn't listening to Ben. She hasn't phoned yet. We won't leave tomorrow. You shouldn't yell.	Ben is talking to Ted, isn't he? Mary has phoned Bob, hasn't she? They will come later, won't they? She can play the piano, can't she? Ted isn't listening to Ben, is he? She hasn't phoned yet, has she? We won't leave tomorrow, will we? You shouldn't yell, should you?
And if there is no auxiliary: use the auxiliary DO
These truckers always look out. Burt usually drives to his work. They forgot their homework.	These truckers always look out, don't they? Burt usually drives to his work, doesn't he? They forgot their homework, didn't they?