第一个Had是助词have的一般过去时,第二个had是实意动词have的完成时,实意的have通常需要一个宾语.比如 have supper.吃晚饭,所以我认为你的问题应该是----什么时候用过去完成时. 讲过去发生的事用一般过去时 I had lunch 40 minutes ago. 讲过去发生的事,但是不想讲什么时候,就想说你做过了,可以用现在完全时 I have had lunch. 实际上,一般过去时和现在完成时没有什么大区别. 如果你本来在讲过去发生的事儿,结果讲着讲着,你又需要讲一个更早发生的事儿,你就得用过去完成时了. Wenn I rushed to the Airport, the plane had already taken off. 当我冲到机场的时候(这是过去发生的事儿,要用一般过去时), 飞机已经起飞了(飞机起飞这一事件发生在你冲到机场之前,所以要用过去完成时)

"had had" is the past perfect form of "HAVE" Past Perfect: HAD + Past Participle GO --> had gone WORK --> had worked HAVE --> had had Use the past perfect when two actions happened in the past and you want to show which one happened first. "I had had an interview with the local manager before the head of the company interviewed me." "By the time she entered the university, she had had three children."