Have had/had had

[kindaichi]

Hi.I am having problem with have had/had had.I bought a lot of books already,but still,all the explanation in the books doesn;t seem to satisfy me and i still don't get the idea.Why some sentence have "have had/had had"?Can someone kindly provide me a detail explanation with examples?Thank you

[Mariner]

Let's start with an example:

I had already had breakfast when the phone rang

In this example, the had marked in red is auxiliary, while the green functions as a main verb.

Consider a similar example with eat
I had already eaten when the phone rang

Same logic with have

[MikeNewYork]

Originally Posted by kindaichi

Hi.I am having problem with have had/had had.I bought a lot of books already,but still,all the explanation in the books doesn;t seem to satisfy me and i still don't get the idea.Why some sentence have "have had/had had"?Can someone kindly provide me a detail explanation with examples?Thank you

The problem is that the verb "have" can be a main verb and an auxiliary verb. We form the present perfect tense with "have" and the past perfect with "had". This is true even when "have" is the main verb.

I have had breakfast. (present perfect)
John had had breakfast before I had mine. (past perfect)