Hello
why we have to say is.. if you did exams, that result with you for every. In this case we must use have or has.Here we are saying about third person so has will take place infrount of visited.
For example if you taken food... how we can discous issue.... gernely we will ask like this about third person...
Ramesh had his lunch? here there is no result.. just he finished work...
I hope now you understood where to use have, has , had