请教OG12-27关于estimate的用法

舟楫

27. Paleontologists believe that fragments of a primate jawbone unearthed in Burma and estimated ”at 40 to 44 million years old provide evidence of“ a crucial step along the evolutionary path that led to human beings.
(A) at 40 to 44 million years old provide evidence of
(B) as being 40 to 44 million years old provides evidence of
(C) that it is 40 to 44 million years old provides evidence of what was
(D) to be 40 to 44 million years old provide evidence of
(E) as 40 to 44 million years old provides evidence of what was

答案是D
OG解释说the verb estimated should be followed by the infnitive to be, not the preposition at-unless the
writer intends to indicate a location at which someone made the estimate.
请问unless the writer intends to indicate a location at which someone made the estimate. 这句话是什么意思，也就是什么时候使用estimate at呢？

舟楫

我刚开始也被OG的解释忽悠了，其实很简单，它那句话就是要说如果这个estimate是在XX地做的，而作者要表明这个地点，就用estimate at somewhere。。。表示某人在XX地做了estimate。
一般表示时间或者年龄的话都是用estimate to be. 我不知道这是不是什么语法“定理”，只是通过对og11 og12的总结获得的。
希望对你有帮助

-- by 会员 lpilikeit (2010/8/26 9:03:39)

很有帮助，非常感谢！！

lpilikeit

我刚开始也被OG的解释忽悠了，其实很简单，它那句话就是要说如果这个estimate是在XX地做的，而作者要表明这个地点，就用estimate at somewhere。。。表示某人在XX地做了estimate。
一般表示时间或者年龄的话都是用estimate to be. 我不知道这是不是什么语法“定理”，只是通过对og11 og12的总结获得的。
希望对你有帮助