重点讲解：
1. piece together 拼凑出（真相）；
They've pieced together his movements for the last few days before his death.
他们已理清了他去世前几天的活动情况OYvA[GRoFM。
2. wipe out 摧毁；毁灭；使灭绝；
The spill could wipe out the Gulf's turtle population.
这次原油泄漏可能会使波斯湾的海龟灭绝wcrX3Pe|Dmw%KqPQZ[y。
3. pin down 确定；证实；
It has taken until now to pin down its exact location.
直到现在才确定了它的准确位置Ede=4VMrhfeNsFrubG。
4. shed light on 使（某事）显得非常清楚；使人了解（某事）；
A new approach offers an answer, and may shed light on an even bigger question.
新的方法提供了一个答案，并且可能让人们对一个更大的问题有进一步的了解O@Yys64.%+yNy。