Chinese languages

The reason behind it is because for example, when you have two syllables both with third tones, it'd be difficult to pronounce, therefore it's modified to allow speakers to speak more smoothly. I'm not fluent in Cantonese so I can't answer that part of your question, sorry.

Many Chu Nom characters are actually the same as Chinese Hanzi. However, there are many that basically consists of two parts, one that indicates the pronounciation in Vietnamese and the other indicate the meaning.

I heard a phrase used in the movie 風雲, "此乃是非之地". That got me wondering: Is the subject of the sentence "是非之地" (i.e. "decision ground") or "非之地" (i.e. "evil ground").