Be strong on
I'm not too strong on organic chemistry, so I'm going to get a tutor this semester.
Be low on
We are running low on rice.
Be long on
He was short on patience, but long on a sense of his own worth.
Be short on
The president’s speech was long on colorful phrases but short on solutions.
I think that 'on' is used to convey the meaning of "regarding"
But why is it incorrect to say this way?
- Be good on
I'm not very good on predictions