I have a certificate in American sign language.

How many talents you have! Perhaps we will never know them all.

If you want to brighten his day..., just learn a comon greetings in sign language

That's good advice, I hadn't thought of that for some reason. After all, we have the Internet and, if you wish, you can learn anything.

I have used it to assist medical practitioners

I am impressed by how socially active you are. It is even more impressive that such a person was forced to be in the position in which you are now. Sometimes it seems to me that this world is not created for good, although in reality it is not.