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.a single ancestor’s who is thought to have lived
B.a single ancestor’s who was thought to live
C.a single ancestor whom it is thought had lived
D.the Y chromosome of a single ancestor who is thought to have lived
E.the Y chromosome of a single ancestor whom it was thought had lived
答案d 我选c c是有问题thought后面应该加个that是吗？谁能给解释下“the y chromosome
of a single ancestor”是个什么结构么？ 作者: min356478 时间: 2010-9-22 07:01
the y chromosome of a single ancestor 是 A of B结构
这两道题很像呢~
1.According to scientists at the University of California, the pattern of changes that have occurred in human DNA over the millennia indicate the possibility that everyone alive today might be descended froma single female ancestor who lived in Africa sometime between 140,000 and 280,000 years ago.
(A) indicate the possibility that everyone alive today might be descended from a single female ancestor who
(B) indicate that everyone alive today might possibly be a descendant of a single female ancestor who had
(C) may indicate that everyone alive today has descended from a single female ancestor who had
(D) indicates that everyone alive today may be a descendant of a single female ancestor who（D）
(E) indicates that everyone alive today might be a descendant from a single female ancestor who
前后（粉色底的）是并列关系，所以排除C，
be thought to be是固定用法吧，***被认为*** 作者: 小月潇湘 时间: 2010-9-23 10:45
D.the Y chromosome of a single ancestor who is thought to have lived
A.a single ancestor’s who is thought to have lived
A和D的区别就在前半段吧？我想问问说all C 都是从一个祖先的C传下来的，我们怎么判断这个说的是the Y chromosome of a single ancestor 而不是the Y chromosomes of a single ancestor 呢？为了让这个染色体也有复数的可能我选了A。。。。作者: tania_zhang 时间: 2010-9-24 08:37
我明白了，这个a single ancestor's who。。。这里的who的先行词是一个所有格形式，也就是指的是染色体，显然不是染色体住在。。
我的理解对吗作者: laurawang2234 时间: 2010-9-24 19:54
看着看着觉得d是正确的作者: acrophobia 时间: 2010-9-25 06:50
have lived怎么可以和ago搭配呢？作者: stucashS 时间: 2010-9-25 19:58
其实我的疑问是为什么这里用who is thought to have lived ，为什么是完成时呢？作者: seanceserene 时间: 2010-9-26 06:52
