Hello, Ambar! In this case I would use "he hasn't come back yet". If you were to say, "he isn't back yet" then that would be correct and mean the same thing. However, "he isn't come back yet" sounds strange and would be incorrect. I hope that helps. Best of luck with your studies! :-) -Charlie

You should say: He has not come back yet. this means "we expected him to come back, but this didn't happen" "is not come back" is grammatically not correct.