I/we should have been working.
将来完成进行时与将来完成时的关系和现在完成进行时与现在完成时的关系一样.即在以下情况下可以用将来完成进行时而不用将来完成时:
1 动作本身就是连续的:
By the end of the month he will have been living/working/studying here for ten years.
到了月底他在这里居住/工作/学习就满十年了.
2 一种经常进行的动作被表示为连续的动作:
By the end of this month he will have been training horses/climbing mountains for twenty years.
到了这个月底他驯马/登山就满