Question

When did you first know this bamboo forest?

=> How long ____________________

Answer 1

When did you first know this bamboo forest?

=> How long _have you known this bamboo forest?___

Mình nghĩ là như vầy?!

Answer 2

=> How long have you been knowing this bamboo forest?

Answer 3

When did you first know this bamboo forest?

=> How long _____have this bamboo forest been known by you? _______________

=> How long _____have you been knowing this forest?____

Answer 4

->How long is it since you first knew the bamboo forest?