How to pronounce [o]:
Put the tongue at the bottom of your mouth and push the lips forward into a small “O” circle. The sound of [o] sounds like the “-aw” in English “law”.
How to pronounce [u]:
Push the lips forward hard to make a smaller round gap. The sound of [u] sounds like the “oo” in the English word “wood”.
How to pronounce [ü]:
Try to pronounce the pinyin final [i] or “ee” in English word “bee”, and then gradually round and tighten your lips in an “O” shape. Make it faster! Combine these sounds together. The vowel [ü] will naturally come out.
The Similarity:[o] [u] and [ü], these three vowels are the essential basic finals in Chinese Pinyin.
Lips’ shape: [o] [u] and [ü] all have the round “O” shape.
1. The round “O” shape gets smaller and smaller in this order:[o] > [u] > [ü]
2. The initial [j]/[q]/[x]/[y] can never spell with [u]. Thus, the syllables “ju” “qu” “xu” “yu” are actually all in [ü] sound, but written as [u].