。。SC句意不明。。求大N相助

winzero

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

	a single ancestor's who is thought to have lived
	a single ancestor's who was thought to live
	a single ancestor whom it is thought had lived
	the Y chromosome of a single ancestor who is thought to have lived
	the Y chromosome of a single ancestor whom it was thought had lived

本题答案是D。但是- -很奇怪为什么可以用have lived。。。。已经生存在14000年前？？

s2206001

你这个是出自曼哈顿的模拟题还是？

尝试分析一下，首先排斥CE，应该没问题吧，因为定语从句出现了it，所以错。排除AB是因为用了所有格形式，因为前面没有所属关系，这里出现所有格的省略形式无法理解。就剩下D了。就算不这样排除，AB的定语从句也是错误的，不能这样用定语从句修饰所有格的主词，因为所有格就是一个完成单词，这个和of从属有区别。

对于你说的完成时，是因为表示过去，动作已经结束。