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 (D) E. sloth which, found in Puerto Rico in 1991, was dated at 34 million years old, made the sloth the earliest known mammal of
其他各种it,this 不能指代导致出错我都能看出来然后排除来选择，但是我就是不明白为什么要用 have been dated at 时态？？搜CD上的帖子发现没人有这个疑问，，，呃，，这个怎么理解？难道是一直被鉴定为34 m old？年份鉴定不是应该是过去式么。。。？说不通啊我觉得。。。希望有大神解决下我这个小小的问题。。。。谢谢！！
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发表于 2013-4-19 13:21:22
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