1.the mystery of ……的谜题；……的奥秘
The mystery of how brain cells are killed off by degenerative neurological diseases is no different.
关于脑细胞是如何被质变的神经疾病杀死的奥秘跟这没有什么不同。

2.a fragment of 一块..的碎片
I am a fragment of a mirror whose whole design and shape I do not know.
我是一块镜子的碎片，我不知道镜子的完整的形状。

来源:可可英语 http://www.kekenet.com/Article/201703/499162.shtml