All Y chromosomes in existence today aredescended from a single ancestor’s who is thought to have lived about140,000 years ago.
A. asingle ancestor’s who is thought to have lived B. asingle ancestor’s who was thought to live C. asingle ancestor whom it is thought had lived D. theY chromosome of a single ancestor who is thought to have lived E. theY chromosome of a single ancestor whom it was thought had lived
答案是D。但是为什么是完成时。。。（原文最后的时间是ago，不应该是过去时么？）作者: lexuefeifelix 时间: 2013-1-19 19:44
信息提供人不是直接陈述者 thought to have done,claimed to have done,believed to have done............作者: lexuefeifelix 时间: 2013-1-19 19:48
http://www.chasedream.com/show.aspx?id=607&cid=41作者: kobeheorin 时间: 2013-1-20 06:03
灰常感谢，明白了！～！