Smart dog!

I read HENRY AND MUDGE - Take the Big Test.

Henry, his mother and his dog Mudge saw a clever dog.
The dog was following orders of the man. He said "Stay" and he walked to somewhere. Surprisingly, the dog had stayed until the man came back.
What a clever dog it was!

Then, Henry decided to make Mudge go to a dog school because Mudge had some bad habits. The dog was trained by a good teacher, Mr. Papp.
After he trained Mudge, the dog had big test. Henry said "Stay" and he walked away.

Did Mudge do well?

Please read the end.