The vowel "ün" removes the above two points, only in the following two cases:

(1) When the vowels in the n series are spelled with initials J, Q and X, they are written as Jun, Qu and Xun, and these two points should be removed.

(2) When the vowel of column ü n is spelled with the initial "y", it is written as: yun, and the two dots should also be removed.

ün and un are vowels, and the sound ün is the same as "dizzy".

Un is the vowel of the words "yun" and "hun", which is incorrect. The vowel of rhyme is "ün" and the vowel of muddy is "un".

When vowels in column ün are spelled with initials N and L, they are still written as N (female) and lü (LV), and two points cannot be removed.

Extended data

1958, 1 1 In February, the fifth session of the first National People's Congress passed the Resolution of the National People's Congress on the Chinese Pinyin Scheme, and the first legal Latin alphabet Chinese Pinyin Scheme was born in New China.

Many rules for spelling Mandarin syllables with the Chinese Pinyin scheme mainly involve the use of vowels, such as using Y and W, omitting the additional symbols on Mi and yu, and omitting the rhymes of iou, uei and uen.

As for iou, uei and uen, these are only theoretical spelling forms, which will never appear in practical application, because when they are zero initial syllables, you, wei and wen should be written according to the usage rules of Y and W respectively, and when they are combined with consonants, iu, ui and un should be omitted.

Tone is an important part of Chinese syllables, which plays a unique role and is an indispensable element of a syllable, so the Chinese Pinyin Scheme specifically stipulates tone symbols. Tone symbol is the standard mode of inheriting phonetic symbols. These four key signature's intuitively show the rising and falling characteristics of the four tones in Putonghua, which has certain advantages.

Baidu Encyclopedia-Chinese Pinyin Scheme