2.4 Where Do Tone Marks Go in Pinyin? Simple Rules You Must Know
Tone marks are always written on the main vowel of the syllable.
Main vowel priority order: a > o > e > i > u > ü
- āi, ōu, iē, iā, uō
⚠️ Exception Rule
When i and u are combined in the same syllable, the tone mark goes on the second vowel:
- iu → jiǔ, liù
- ui → chuī, suí, tuǐ, guì