高中英语语法问题!急
1.WhethertheSumerianswerethefirstpeopletodevelopwritingisuncertain.
为什么这句不用不定时的完成时态呢?E.g.WhethertheSumerianswerethefirstpeopletohavedevelopedwritingisuncertain.developwriting不是过去发生的事情吗?为什么不用tohavedeveloped呢?
2.Helenneversubmitsanythingtoaneditoruntilrevisingitseveraltimes.请问这句中
revisingitseveraltimes"的主语是什么?是Helen还是editor?如何找主语啊?我怎么都分不清.