as soon as 引导后加过去时表示过去将来 这句话里为什么用完成时

问题描述:

as soon as 引导后加过去时表示过去将来 这句话里为什么用完成时
I will start writing my next paper as soon as i have finished this one

I decided to go to the library as soon as i finished what i was doing
一个后面加过去式 一个加完成时
什么原因 求解释

第一句强调完成动作,做完以后才start writing.
第二句decided和finished一致,没有问题,finished过去正在做的也没有问题.都是相应的过去式.
多谢你的问题!