求教：应该用过去完成时的时候，前面有to，用现完这种规律

kiki070300123

1. All Y chromosomes in existence today are descendedfrom a single ancestor 's who is thought to have lived about140000 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 wasthought had lived

同类型的题目

Combining enormous physical strength with higher intelligence, theNeanderthals appear as equipped for facing any obstacle the environmentcould put in their path, but their relatively sudden disappearanceduring the Paleolithic era indicates that an inability to adapt to someenvironmental change led to their extinction.

A)appear asequipped for facing any obstacle the environment could put in their path,

B)appear to have been equipped toface any obstacle the environment could put in their path,

C)appear as equipped to face any obstacle the environment could put intheir paths,

D)appeared as equipped to face any obstacle the environment could put intheir paths,

HarrisZheng

道理很简单 不定式to后面要接动词原形 所以不定式后面是没有过去完成是时的