The house of Babel

Auxiliary word 啊(ā) is put in the end of the sentence to express surprise or admiration mood. The sound would change according to the front phonemes.

1, if the front phoneme is i, 啊(ā) sounds like 呀(yā)

笔啊–>笔呀

2, if the front phoneme is u (ɑo iɑo), 啊(ā) sounds like 哇(wā)

好啊–>好哇

3, if the front phoneme is n, it sounds like 哪(nǎ)

天啊–>天哪

For foreign students, it is boring to remember all of the rules. I think, once you practise that and form a habit , it comes natural to you.

Not only languages but also other skills, after you practice a lot, it will make perfect .