题目选项分析

Paleontologists believe that fragments of a primate jawbone unearthed in Burma and estimated as 40 to 44 million years old provides evidence of what was a crucial step along the evolutionary path that led to human beings.

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.