Having been bitten by the snake,she was frightened at it.（这个

一、二者表达的意思不同：Bitten by the snake 表示就在被蛇咬的那个时候或者同时,而 Having been bitten by the snake 表示在被蛇咬了以后。二、过去分词的一般式表示与句子谓语动词同时或接踵发生的动作,而现在分词的完成被动是表示动作发生在句子的谓语动词以后。三、下面把两种情况分别改写为状语从句：1) Having been bitten by the snake,she was frightened at it。改写为：After she had been bitten by the snake,she was frightened at it。2) Bitten by the snake,she was frightened at it。改写为：When（或 as soon as) she was bitten by the snake,she was frightened at it。