——several times,they need some encouragementa.failedb.having failed在非谓语中done 和having done 有什么区别

done表示被动,而having done表示主动,并且是doing 的完成时,表示发生在位于动词之前.如 Given more time ,i can do it better.(我被给时间）Having read abut the ,i was not surprised at it when they told it to ...