having been done是什么时态 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. 

本文最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；