[求助] gwd 31-28

答案是C吗？GG有什么不解的地方？

根据主语samples判断谓语为复数，排除AB；and 后边要补出are，排除D；be dated at这种用法好像没见过吧，被我排除了，剩C。

I choose C, but sb choose E, I am not sure the usage of be dated at and be date to be, Can somebody give me a confirmation? thanks

i think the dated at will be better

同意C

答案　是E，

看看下帖，很多真题。（有这题）

http://forum.chasedream.com/dispbbs.asp?boardID=23&ID=143014&page=3

我想选E

GWD13-28
Q28:
Fossils of the arm of a sloth found in Puerto Rico in 1991, and dated at 34 million years old, made it the earliest known mammal of the Greater Antilles islands.

A.sloth found in Puerto Rico in 1991, and dated at 34 million years old, made it the earliest known mammal of
B.sloth, that they found in Puerto Rico in 1991, has been dated at 34 million years old, thus making it the earliest mammal known on
C.sloth that was found in Puerto Rico in 1991, was dated at 34 million years old, making this the earliest known mammal of
D.sloth, found in Puerto Rico in 1991, have been dated at 34 million years old, making the sloth the earliest known mammal on
E.sloth which, found in Puerto Rico in 1991, was dated at 34 million years old, made the sloth the earliest known mammal of