Chinese

		must not; should not; not be allowed	and; as well as; but (not) and; as well as; but (not); yet (not); (shows causal relation); (shows change of state); (shows contrast)	to know; to be aware
simp. and trad. (不得而知)		不得	而	知

Idiom

不得而知

1. to be unable to know or find out; to remain unknown; to be unable to ascertain