下句为什么不用过去完成式

问题描述

This was later confirmed by a naval official at the Ministry of Defence after the Elkor had returned home.
All the items that were found were sent to the War Museum.
第一句当中 after the Elkor had returned home用了过去完成时，
第二句当中 that were found 为什么不用that had been found?

老师答疑

曹老师：

before和after引导时间状语从句时，由于连词已经清楚说明了主句和从句谓语的时间先后，因此先发生的动作可以用完成体，也可以用一般体。都是正确的。

当按照事件发生的顺序进行描述时，说话人的思绪（即说话人关心的时间点）也会沿着时间轴的方向移动，于是在说话人看来一个个的事件都是发生并结束了的事件，都用一般体来描述。如果后面描述的事件发生与前面描述的事件之前，则必须用完成体。

陈老师：

This was later confirmed by a naval official at the Ministry of Defence after the Elkor had returned home. 

参考译文：埃尔科 回到家之后，这件事后来被国防部的一名海军官员所证实/确认。

All the items that were found were sent to the War Museum.

参考译文：所有被发现的物品被送往战争博物馆。
第一句当中 after the Elkor had returned home用了过去完成时，
第二句当中 that were found 为什么不用that had been found?

解答如下：

(1)第1句已经有连词after很明显的表示动作先后的连词，因此先发生动作用过去完成时态，后发生用一般过去时态.

(2)没有连词或者其其他方面暗示明显的动作时间先后，一般过去式也是可以的。如果有明显动作先后，先发生用过去完成时态。