I waited until he had finish his homework中,为什么until后面是过去完成时,怎么不是一般现在时?

问题描述:

I waited until he had finish his homework中,为什么until后面是过去完成时,怎么不是一般现在时?

wait 用的是一般过去时,
完成作业这个动作在wait之前,故用过去完成时如果wait不是过去式那该怎么写后面的用一般过去时