<i>Do I have to pay for it?<br/></i><br/>I would answer with<i> Yes, you do </i>or<i> No, you don't.<br/><br/></i>Is it possible to answer <i>Yes, you must</i> or <i>Yes, you have to</i>? Perhaps to emphasize the fact that it <i>has to/must</i> be paid.<br/><br/>As for the negative answer, is it possible to say <i>No, you don't have to</i> instead of <i>No, you don't</i>?<br/><br/>Thank you in advance.<br/><i><br/><br/></i>