Excuse me, sir. I've made a tough decision and here is my resignation.
I am sorry to hear that. Why do you want to quit?
I'm sorry to bring up my resignation at this moment, but I've decided to study abroad.
All right. Welcome back anytime.
Thank you, sir. I'd like to say that I'Ve really enjoyed working with you. However, I think it's about time for me to leave.
I am glad to work with you, too. Good luck!