на каком языке говорят в

what language do they speak in

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phrase Rare #30,211
what language do they speak in The final «в» is followed by the place being asked about.
RU: На каком языке говорят в Канаде?
EN: What language do they speak in Canada?

На каком языке говорят в Мексике?

What language do they speak in Mexico?

На каком языке говорят в Швейцарии?

What language do they speak in Switzerland?

Интересно, на каком языке говорят в Бразилии.

I wonder what language they speak in Brazil.

На каком языке говорят в Афганистане?

What language do they speak in Afghanistan?

На каком языке говорят в США?

What language do they speak in the USA?

На каком языке говорят в Австралии?

What language do they speak in Australia?