Excellent! Perfect! Brilliant! Fantastic! Magnificent! Phenomenal! Terrific! You're doing great! Fantastic job! You did a great job! I like that! Well done! Very good! Good. That’s nice. Right. Fine. Quite right. That’s right. That’s it. That’s perfectly correct. That’s correct. That’s quite right. Yes, you’ve got it. You’ve got the idea. Exactly. There’s nothing wrong with your answer. What you said was perfectly all right. You didn’t make a single mistake. That’s exactly the point. That’s just what I was looking for.
Если человек делает успехи: That’s (much) (a lot) better! You are improving. You have made a lot of progress.
Если человек ошибся: Not quite right, try it again. You were almost right. That’s almost it. You’ve almost got it.
Not really. Unfortunately not. I’m afraid that’s not quite right. Good try, but not quite right. Not quite right. Try again. Not exactly.
That wasn’t very good. That was rather disappointing. You can do better than that.