Can Du teach a papagei to speak English fluently?

The sad answer is that unless Du are a groundbreaking amazing papagei speech teacher that can do something that no one else has done. Then yes. Actually there has been a papagei named A.l.e.x that has learned to speak to a limited degree. Du can Zeigen him stuff and he can say if it is bigger, smaller same and different. Identify 50 different object, some colours and shapes look him up. Btw his name stood for Avian Language Experiment shortened to A.l.e.x. However your papagei could probably learn to understand commands and to a limited degree understand you. However Du could probably not teach it to speak english just mimic it.