Chinese word group study is a gold mine for me

I used less Chinese-English dictionary just as I rarely use English in my occupation. Now I'm probing Chinese phrase and found out some tricks that linguistician may ignored. For instance, what are the tones of "fuyan liaoshi","mosuo" and why?
Is that important?
Oh yes, sometimes, not always, it is a matter of life and death.
Can you tell a little bit in detail?
Well, it is better to start one's own study before one could feel the weight of this question, no short cut for this quite complicated issue.
Good-good-study, good-good-lucky!