Has is defined as to possess or own something. An example of has is to own a restaurant.
Usage of "Have Had"
Si può anche chiedere: did you have or had dinner? "Have you had your dinner?" Is the correct sentence. The verb ‘have had’ is in present perfect tense. This verb describes whether you have just completed the action of taking dinner or not.
Meaning of "Have You Eaten"
The person is basically asking you whether you already had your dinner/lunch/breakfast. Sometimes, it is an indication that they want to invite you out. Sometimes, it is an indication that they worry about you. Sometimes, it is just an indication to know what you ate that time.
Usage of "Had Had"
"Had had" is correct. Even "had had had had had had had had had had" can be correct given a convoluted enough scenario and a little punctuation. But "had had" does sound a little weird, so much of the time you’re probably better off writing around it.
Correctness of "I’ve Had Enough"
"I have had enough" is in the present perfect tense. It’s used where time is not mentioned. Example: I have had enough, can’t eat any more.
