标题: 求助--OG--Fossils of the arm... [打印本页] 作者: lyy_chasedream 时间: 2017-8-29 16:59 标题: 求助--OG--Fossils of the arm... 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
答案：D。看过一些解析后可以通过排除法选出D答案。
on the island，排除ACE；
fossils是复数，BCE的动词用了单数形式，排除；
making而不是made，排除AE。
但还是有疑问：
1.一定是on the island吗？只有这一个固定搭配吗？
2.不理解D答案中为什么是have been dated？