"Do you love Aberystwyth?"
Translation:Dych chi'n caru Aberystwyth?
It's just like French: 'wyt ti' is 'es-tu' and 'dych chi' is 'êtes-vous'. Scots Gaelic (but not Irish) has a similar arrangement. Some other languages have a somewhat similar, but not identical arrangement. 'Ti' was singular and 'chi' was plural. But the plural is now used for the singular when being polite. English has now abandoned the singular (art thou) completely but you find in Shakespeare. So the answer to the question is simply that they have to teach you both forms.