-o is noun- so that's easy
-u is who, and I remember it by thinking about "you"
-al - I think of Al Bundy being blamed on Married with Children.
I'm struggling with a pneumonic for -el vs -e but I have begun imagining "Where in E world is Carmen Sandiego" vs a leg moving for -el.
These are just crutches until it becomes natural, but with just a handful, I remember both the question and T- form (not sure what it's called).
I wish other languages were this easy...
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