1.an: half, disk, slow, reverse, Dan.

2. Ian: Border, electricity, money, sky, see?

3.uan: breaking, assembling, wearing, rolling and closing.

4.4. Yuan: Power, security, circle, election, persuasion.

Vowels in Putonghua are divided into monosyllabic vowels, complex vowels and nasal vowels. Nasal vowels are vowels consisting of one or two vowels followed by a nasal consonant. An, ian, uan and üan belong to nasal vowels.

Extended data:

Thirty-nine vowels * * *, including sixteen nasal vowels * * *, that is, an ian uan an en in uen ang ang ung eng ong. Putonghua clearly distinguishes two groups of vowels ending in -n and -ng. Vowels ending in -n are called anterior nasal vowels, and vowels ending in -ng are called posterior nasal vowels.

Anuan ü an belongs to the pre-nasal vowel, and its pre-nasal vowel pronunciation skills are as follows:

One; one

The tip of the tongue is pressed behind the lower teeth, the mouth is opened, and the tongue position is raised from the central lower A position. Finally, the front of the tongue touches the front of the hard palate to block the airflow, so that the sound and breath pass through the nasal cavity, and the front nose and tail disyllabic an is issued.

Ian.

The tip of the tongue abuts against the back of the lower teeth, and the tongue position drops from the front high vowel I to the semi-low vowel A (actually E), and then the tip of the tongue or the front of the tongue is lifted to contact with the gums; Block the airflow, let the sound and breath pass through the nasal cavity, and the front nose and tail emit complex tones, ian.

uan？

Round your lips first. The tongue retracts, and the tongue position is raised from the rear high vowel U to the front low vowel A, close to the upper gum. At the same time, the lips change from closed to open, and then slightly open, making complex tones uan at the front nose and tail.

üan

First, hold your lips and put the tip of your tongue against your lower teeth. The front of your tongue stands up at the U, then descends to the first half of the vowel A (E), and then rises rapidly to contact with the upper gum, blocking the airflow through the nasal cavity. Lips spread out slightly from the cracks, revealing the front nose and tail.

References:

Yun-Baidu Encyclopedia