I was walking along a street in Kaohsiung with a British man who had been living in Hong Kong with his Chinese wife. I thing it was about 7 or 8 pm.
A group of about half a dozen teenage girls in school uniform inside the MacDonalds spotted us and came out. They spoke to us in English.
They wanted help with their homework. They had an assignment to describe the differences between the Taiwanese education system and the western ones. So they were in luck having snagged a teacher.
The British gent proceeded to describe they British system. I finally learned the difference between A levels and O levels. After this, I talked about the Australian system.
A few times they had troubles understanding us. On these occasions the Chinese wife would repeat what we had said and maybe provide an explanation. I found it interesting that they would not understand the Brit or I speeding English, but the same words said by the Chinese woman were understood.
So I formed a new hypothesis. They understood her because she was consistent in the tones she used. I supposed she spoke English words in first tone. As time I became more convinced of this, though I think the total accent is probably more likely the main driver. They seemed to speak English words in first tone. I guessed that a first tone and would hold a different meaning to a second or fourth tone and. I also suspect that westerners do not use third tone much.
Once our homework help was completed they thanked us and we went in our way.