求大神解惑

Yourcent · 发表于 2017-7-28 15:15:51

为什么是现在完成时 have lived，而不是过去完成时had lived呢？祖先不是很久的过去时刻完成生活这个动作吗

All Y chromosomes in existence today are descended from a single ancestor's who is thought to have lived about 140,000 years ago.

Aa single ancestor's who is thought to have lived
Ba single ancestor's who was thought to live
Ca single ancestor whom it is thought had lived
Dthe Y chromosome of a single ancestor who is thought to have lived
Ethe Y chromosome of a single ancestor whom it was thought had lived

正确答案：D

Yourcent · 发表于 2017-7-28 15:21:35

顶楼主！

XQIANG · 发表于 2017-7-28 15:34:06

在不定式短语中添加have，不表示完成时，而是表示的是“先时性”。在本题中即，“生活在140,000年之前”是发生于“认为（thought）”这个动作之前的，所以用to have lived。（先时性是Helr的一个语法概念）

Yourcent · 发表于 2017-7-28 15:44:34

XQIANG 发表于 2017-7-28 15:34
在不定式短语中添加have，不表示完成时，而是表示的是“先时性”。在本题中即，“生活在140,000年之前”是 ...

哇，原来如此，O(∩_∩)O谢谢

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