When did you first know this bamboo forest? => How long ...

rewrite the second sentence so that it has a similar meaning to the first sencence.
1, when did you first know this bamboo forest?
how long.............................................
2, i can't have lunch with you now.
i wish .....................
3, the teacher punished this pupil beacause he was very lazy.
this boy was very lazy so................................................
4, she asked me , " why are you learning English ?"