Text to speech detects wrong language on iPhone

I use text-to-speech (speak screen) on my iPhone (iOS 10, system language set to English) to read out articles I need to read. But it has problem of detecting correctly the languages of the articles. Very often it reads Spanish text in English prononciation, or Chinese text in Japanese. I can't find a way to manually select the language when launching speak screen. What's worse, some of the corrected read Spanish text in iOS 9 get wrong in iOS 10.

I did try to set the system language to Spanish, then some of the Spanish text which were wrongly detected can be read correctly. So it shows this error of language detection has nothing to do with the text itself, but iOS' detection method.

Anyone can help? Thank you!