How to say in Czech: How good is his Arabic?

English
How good is
Czech
Jak dobře umí arabsky?
His Arabic is getting better.
His Arabic is very good.
How do you say that in Arabic?
I do not speak Arabic very well.
You speak Arabic very well.
His native language is Arabic.
Is he learning Arabic on his own?
Arabic is a difficult language.
Arabic is difficult.
He is learning Arabic.

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