How to say in Czech: Are they learning Vietnamese?

English
Are learning
Czech
Učí se vietnamsky?
Are they learning Vietnamese on their own?
They are learning Vietnamese.
Where did they learn Vietnamese?
Do they speak Vietnamese?
They do not speak Vietnamese.
They do not speak Vietnamese very well.
They speak only a little Vietnamese.
They speak Vietnamese.
They speak Vietnamese fluently.
They speak Vietnamese very well.

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