…不得而知
cannot be known; no one can tell
Structure
疑问（谁／什么／为什么／是否…） ， （已／尚／至今） 不得而知
What it means
Classical ‘cannot be known’: closes a sentence whose topic is an open question and says the answer is out of reach.
How it is built
Question clause (谁/什么/为什么/是否/能否) + (已/尚/目前/至今) + 不得而知: 这批竹简是谁埋的，至今不得而知 (who buried the slips is still not known).
When to use it
Formal: history, archaeology, news (具体原因尚不得而知). 已 = no longer knowable, 尚/目前 = not yet, 至今 = still not. In speech: 谁也不知道. 可想而知 (8-6) says the opposite.
Watch out
It takes no object; put the question first. ✗不得而知他的去向 ✓他的去向不得而知.
Examples
这批竹简是谁埋在井里的，至今不得而知。
Who buried these bamboo slips in the well is still not known.
他后来去了哪里，史书没有记载，我们已不得而知。
The histories do not record where he went afterwards, and we can no longer know.
这项政策能否达到预期效果，目前尚不得而知。
Whether the policy will have the hoped-for effect cannot yet be known.
Learn this in Lesson 174 · HSK 7–9: 三星堆 (Sanxingdui)
A dialogue, a reading, word cards with audio and a drill that uses it, in Learn Chinese with Bao. The first lessons of every level are free.
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