“Let’s say you’re asking me to write something in a specific language. Now, I’m fluent in English and Spanish, but your project is in Chinese. Since 
I don’t understand Chinese, I’m not your best option. You need someone who is fluent in this specific language. See?”

He said he did and thanked me.

The next morning, I got a call from another developer asking, “Why is 
So-and-So asking us if we’re fluent 
in Chinese?”