There are two ways to spell syllables.

One is that there is a zero initial I in front of it, which is not a rhyme, so the I in iou is changed to Y → You. [In the zero initial syllable, if I is not a rhyme, I will change it to Y.]

Second, when spelling syllables, if consonants are added in front, the vowels in the middle should be omitted. Such as d-iou→diu.