Normally the Translate app processes the translations online. But you may come across places with weak or no internet access. In that case, you’ll want to download a language in advance so you can use it offline.
Before performing the downloads, make sure you are on a Wi-Fi network with a good connection. Then tap the option for downloaded languages. On the next screen, choose each language you want to download. The app supports Arabic, Chinese Mandarin, Dutch, English, French, German, Indonesian, Italian, Korean, Polish, Portuguese, Russian, Spanish, Thai, Turkish, Ukrainian and Vietnamese.
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Back on the previous screen, you can enable the device mode switch if you want the translations to work offline with the downloaded languages. However, this will prevent you from using languages that you have not downloaded.