不得而知

Function word; no; not; un-; negative prefix; used to form questions or emphasize a statement; sometimes used for rhythm.

Structural particle linking verb/adjective to effect or degree; to obtain, get, gain; suitable; proud; contented; to allow; must, ought to.

A conjunction connecting clauses or phrases; indicates addition, contrast, or a causal relationship; also used to indicate a change of state.

To know; to understand; to be aware of; to recognize; to distinguish; to associate with; to entertain or treat; knowledge or learning.