资料来源 : pyDict

突然,忽然,蓦然,冷不防

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

Sudden \Sud"den\, n.
   An unexpected occurrence; a surprise.

   {All of a sudden}, {On a sudden}, {Of a sudden}, sooner than
      was expected; without the usual preparation; suddenly.

            How art thou lost! how on a sudden lost! --Milton.

            He withdrew his opposition all of a sudden.
                                                  --Thackeray.

资料来源 : WordNet®

all of a sudden
     adv 1: without warning; "all at once, he started shouting" [syn: {all
            at once}]
     2: happening unexpectedly; "suddenly she felt a sharp pain in
        her side" [syn: {suddenly}, {of a sudden}]