Question

When I was a child, I had had to live alone两个had？

Answer 1

第一个 had 是[一般过去时], 第二个 had 是[过去分词]
此句是用了[过去完成时态].
When I was a child, I had had to live alone
过去完成时 :
表示两组动作发生在过去的不同时间的先后次序. 先完成的动作用[过去完成时],
后完成的动作用[过去时]
When I was a child [当我是小孩的时候 (was [过去时] ) ] I had had to live alone [我曾经须要独自生活 (had had [过去完成时] 因为独自生活是童年时的其中一段时间, 所以列为[先完成的动作])

Answer 2

had to是have to的过去分词

Answer 3

过去完成时

Answer 4

过去完成时