How to say in Czech: How good is their Ukrainian?

English
How good is
Czech
Jak dobře umějí ukrajinsky?
Their Ukrainian is getting better.
Their Ukrainian is very good.
How do you say that in Ukrainian?
I do not speak Ukrainian very well.
You speak Ukrainian very well.
Their native language is Ukrainian.
Are they learning Ukrainian on their own?
He is learning Ukrainian.
He is not Ukrainian.
He is Ukrainian.

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