为什么同样是部分倒装 hardly had sb did when……用的是did过去式，而not until ... did sb do用的是do

Question

部分倒装后的动词时态怎么判断

Answer 1

1. hardly had sb did when……应该是hardly had sb done when…did…

因为 had done 的动作发生在 从句谓语did 以前，是属于过去的过去，所以用过去完成时。
Hardly had she sat down when the doorbell rang. "她刚一坐下门铃就响了。"

2. not until ... did sb do 中 did....do 是一般过去时部分倒装句式，其前用did表示过去时态，所以后面用动词原形do.
Not until his father came back did he go to bed last night. "昨晚直到他爸爸回来他才上床睡觉"。

Answer 2

前面的did是跟在had后面的，既然是跟在had后面，had+done，当然是用动词的过去分词。而后一个，do是跟在did后面的，这里的did是助动词，跟在助动词后面当然要用动词原型。