30.正确选项是D,即：Paleontologists believe that fragments of a primate jawbone unearthed in Burma and estimated to be 40 to 44 million years old provide evidence of a crucial step along the evolutionary path that led to human beings.
OG给出的解释是estimated 应该跟to be表示年纪的预估。
而140题，正确选项是E,即：Rock samples taken from the remains of an asteroid about twice the size of the 6Timile-wide asteroid that eradicated the dinosaurs have been dated at 3.47 billion years old and thus are evidence of the earliest known asteroid impact on Earth.
OG给的解释是：The idiomatic wayof expressing estimation of age is with the phrase “dated at”.
我不明白为什么后面跟年纪一会是at,一会又是to be,这个有具体的区别吗？？？
谢谢大家的帮助！作者: ItalyPirlo 时间: 2013-4-22 19:28
亲~to be是跟在estimate后面的固定搭配，at是跟在date后的固定搭配。和后面的年纪木有关系哦~因为年纪前可以有的介词多了去了~
另外，date at 后接···years old
date to 后接···years ago作者: Knightll 时间: 2013-4-24 06:27
