This is an intersting question. I have asked a similar one in this forum and I found out it to be a bit difficult to comprehend the answers if taking into considiration the classical rules. My guess...
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
TicceSometimes a zero article is used with a unique thing or person. For instance,
To elect PRESEDENT (still it can be also THE PRESIDENT in different cases)
Jogn, professor of arts, is a great guy. (it means that there is only one professor of arts)