求助 Fossils of the arm of a sloth -时态问题

小一酱_

之前看到论坛里有人问过这题，但是我不明白为什么正确DB选项里面，dated at 可以用have been 的形式？ 求解答 感谢~！

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

fxxxfxxx

这题的split跟时态没什么关系吧，为什么你觉得这里不能用现在完成时呢？