John received an invitation to dinner,and with his work ____,he gladly accepted it.

问题描述:

John received an invitation to dinner,and with his work ____,he gladly accepted it.
为什么用finished而不用having finished?

看下句子说他的工作怎么了
用finished就是完成了.用having finished 好像是说正在完成了?having sth to be 就是说正在什么什么的意思.不过句子里面表示已经完成了