yan and yang
Not so many foreign can pronounce yan and yang correctly.
The difference between yan and yang in fact is the difference between n [n] and ng [ŋ].
First let’s figure out where we are pronouncing those. When we pronounce n [n], we can feel it is in the front part of your mouth, or oral cavity. When we pronounce ng [ŋ], we can feel it is close the back part of the oral cavity, exactly near to the part that connected to your nose, or nasal cavity.
when you pronounce a[a], you can feel that was in the middle of your oral cavity.
The left thing is to combine a[a] with n [n] and ng [ŋ]. You know, when two pronunciations come together, there is a transition from a[a] with n [n], from a[a] to ng [ŋ]. In such time, you have to pronounce the first part and soon you have to get ready for the second part. As a result, they sound like an [an] and ang [ɑŋ].
After you combine another y, they sound like yan [iɛn] and yang [iɑŋ] respectively.
So be careful, yan is not yang, and yang is not yan.
Also Yin and Yang (阴阳) does not sound like [in n iɛn].