The position of tonal marks:
1、The tonal mark is placed on the vowel.(e.g. fó、hún、lǜ)
2、When there are two vowels, the tonal mark is placed on the earlier vowel in the sequence of: a、o、e、i、u、 ü. (e.g. tiào、bǎi、xióng、gěi)
3、When i and u appear together, the tonal mark is placed on the last vowel. (e.g. xiù、jiǔ、kuī、 shuǐ)
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