【SAT文法】这句话为什么不用完成时?When we counted the growth rings in the ancient redwood stumps,we found that the life of each of these trees spanned many centuries of history.为什么不用had spanned?如果都对的话区别是什么?
问题描述：
【SAT文法】这句话为什么不用完成时?
When we counted the growth rings in the ancient redwood stumps,we found that the life of each of these trees spanned many centuries of history.
为什么不用had spanned?如果都对的话区别是什么?
答
had spanned用 有明确时间先后顺序的时候,eg.I had done my homework before the lunch was served.