[2vlada]

Hello!
I'm currently stadying english. And yesterday teacher asked our class to make a resume of an article. This article was about a boy who was an autist. He couldn't speak, but he could express himself by playing the piano. So, i wrote my resume, and there were one sentence, that wasn't correct, according to my teacher. Could somebody help me with it, please!
They found a boy, who didn't speak, but he could express himself by playing the piano.
or as my teacher proposed:
who doesn't speak, but can express himself...
The boy is still alive, and he still doesn't speak. But we don't have this information in the text. The article was written in 2005.
Thank you!