Having been 是什么时态

Question

Having been lost in the mountains for a week ,the two students were finally saved by the local police.

为什么不是 have been lost

Answer 1

你不要被having 的ing 迷惑住，其实就是现在完成时，只不过做了伴随状语，需要用ing形式来修饰the two students , 所以它的原形就是have been ,
原句可以改成，The two students have been lost in the mountains for a week ,the two students were finally saved by the local police.
只不过为了简便，所以第一句成了修饰成分。

明白了？？呵呵

Answer 2

实际是它就是have been lost，只不过它是个非谓语动语啦，句中主语the two students 与lost可以理解为”主动”的关系，所以就用的Having啦．．实际是它是现在完成时．

Answer 3

就是have been
现在完成时啊`````
用Having是因为它在句首，而且和主语the two students 是主动关系```

Answer 4

having been 这个我还不晓得~~但是have been doing完成进行时，表示动作已经开始，但没有结束，并有可能持续下去。

Answer 5

具体情况具体分析
HAVE BEEN DOING. 现在完成进行时

HAVE BEEN DONE 现在完成时