The scientist confirmed the snake was a previously unknown species after conducting a genetic analysis of tissue samples.
出自-2017年6月聽力原文
According to Leslie, those who ridiculed former Defense Secretary Donald Rumsfeld for his 2002 remark that we have to be wary of the unknown unknowns were mistaken.
2017年12月四級真題（第二套）閱讀 Section B
英語六級真題
What distinguishes a depression from a harsh recession is paralyzing fear - fear of the unknown so great that it causes consumers, businesses, and investors to retreat and panic.
出自-2013年6月閱讀原文
These "thought experiments" were pages of calculations signed and submitted to the prestigious journal Annalen der Physik by a virtual unknown.
出自-2010年12月閱讀原文
Into the Unknown The world has never seen population ageing before
出自-2010年12月閱讀原文
柯林斯高階英漢雙解學習詞典釋義
ADJ
不知道的；不了解的；未知的
If something is unknown to you, you have no knowledge of it.