How to say in Czech: Are they learning Vietnamese on their own?

English
Are learning on their own?
Czech
Oni se učí vietnamsky jako samouk?
Are they learning Vietnamese?
They are learning Vietnamese.
Where did they learn Vietnamese?
How good is their Vietnamese?
Their native language is Vietnamese.
Their Vietnamese is getting better.
Their Vietnamese is very good.
Do they speak Vietnamese?
They do not speak Vietnamese.
They do not speak Vietnamese very well.

Czech phrasebook and translator with tens of thousands of sentences translated by humans. Czechslator is being developed by Michal Měchura. CREDITS Czechslator's sentence generation engine is partially based on Grammatical Framework. All Czech pronunciation is computer-generated using Microsoft Azure Text to Speech. When Czechslator cannot find a translation in its own database, it looks in the PanLex dictionary or obtains a machine translation from Microsoft Translator. PRIVACY Czechslator does not save any cookies in your web browser and does not collect personally identifiable data. Czechslator uses StatCounter for traffic analysis, configured not to save any cookies in your web browser and not to collect any personally identifiable data.