Answer:
1 . I have had lunch .
2. He has had lunch .
3. I had had lunch before you came.
Explanation:
This is one of the most confused about combinations as per my experience .I would firstly tell a bit of grammar part and then clarify with real day to day usage .
THE CONFUSION IF AT ALL COMES IS BECAUSE OF TWO DIFFERENT USAGES OF WORD “HAVE” . THEY LOOK AND SOUND LIKE SAME BUT PLEASE TREAT THEM DIFFERENTLY . So let's separate them like one of them is same like “ “AM,ARE,WILL,SHALL, “ the helping or auxiliary verbs ,and the second. “have “ is just like “ drive, eat, drink, watch” the main verb “ or I prefer to call “ Action”.
