Скобки нужно разкрыть в Present Simple, Continuous, Perfect и Perfect Continuous. : I ... (not to know) how long Henry ... (to work) on that project but he (not to finish) it yet
I don't know [Present Simple] how long Henry has been working [Present Perfect Continuous] on this project, but he hasn't finished [Present Perfect] it yet.
I don't know [Present Simple] how long Henry has been working [Present Perfect Continuous] on this project, but he hasn't finished [Present Perfect] it yet.