资料来源 : pyDict

除非除…之外

资料来源 : Webster's Revised Unabridged Dictionary (1913)

Unless \Un*less"\, conj. [Formerly, onles, onlesse, onlesse
   that, that is, in less, in a less case. See {On}, and
   {Less}.]
   Upon any less condition than (the fact or thing stated in the
   sentence or clause which follows); if not; supposing that
   not; if it be not; were it not that; except; as, we shall
   fail unless we are industrious.

   Note: By the omission of the verb in the dependent clause,
         unless was frequently used prepositionally, -- a
         construction common in Shakespeare and still employed
         colloquially.

               Here nothing breeds unless the nightly owl.
                                                  --Shak.