having been done是什么时态

是现在完成时。Having been done是现在分词的完成时的被动语态，用的时候常常会出现一个段时间状语。having been done强调动作发生在谓语动词表示的动作之前。

Having been done一般强调被动的动作，而且该动作必须和主句动作之间有着明显的时间/逻辑上的先后/因果关系，且隐含having been done的动作不会再进行的意味。

例如：Having been kept in the fridge for two hours, the food has gone bad。此题强调先有“be kept in the fridge”，才导致了后面的“go bad”。 前后动词有明显的先后/因果关系，且隐含了“这食物不会再放在冰箱里保存”的含义了。

造句示例：

1、Having been well tended for half a year, my granny became far better.

被精心照料半年后，我奶奶的情况好多了。

2、In conclusion, the work having been done and being to be perfected are put forward.

本文*后总结了完成的工作，以及日后可以改进和完善的地方。

3、There are two kinds of efforts having been done to solve the problem: one is using novel searching methods, such as Genetic algorithm, Simulated Annealing Algorithm etc;

解决问题的办法有两种：一是用新颖的搜索方法，如遗传算法，模拟退火算法等；