to have done 与having done 有什么区别
问题描述：
to have done 与having done 有什么区别
答
to have done 一般指尚未完成的完成时,属于完成时语态,例如 By the end of next term(尚
未来到) ,we are going to have learnt nine thousand words.
而having done 强调时间上的先后顺序,一般作状语,例如 Having finished
his work,Bob went back home happily.