Special Spelling Rules of [i] / [u] / [ü]

As we already know, the vowels in the Pinyin system can be an independent syllable itself even without the Pinyin initials. But, there is an exception about the vowels [i], [u], and [ü].

When [i], [u] or [ü] makes a syllable by itself:

1. “y” should be added in front of [i] and [ü].

Note:

Note that the two dots above [ü] should be omitted as [u] in written form, but the pronunciation keeps as the original [ü].

e.g.

Spoken pronunciation	Written form
i	Yi
ü	yu

2. “w” should be added in front of [u].

e.g.

Spoken pronunciation	Written form
u	wu

When [i] / [u] / [ü] starts a syllable without other initials:

1. When [i] starts a syllable, it is written as “y”.

e.g.

Spoken pronunciation	Written form
ia	ya
ian	yan
iang	yang
iao	yao
iou	you
iong	yong
ie	ye

Note:

Note that except in “in” and “ing”, “y” is added at the beginning.

Spoken pronunciation	Written form
in	yin
ing	ying

2. When [u] starts a syllable, it is written as “w”.

e.g.

Spoken pronunciation	Written form
ua	wa
uai	wai
uei	wei
uan	wan
uang	wang
uen	wen
uo	wo

3. When [ü] starts a syllable, “y” should be added in front of it, and the two dots above [ü] are omitted which is written as [u].

e.g.

Spoken pronunciation	Written form
üe	yue
ün	yun
üan	yuan