When is the second character of a word a neutral tone?
In non-reduplicated words like 麻烦 (ma2 fan0), 丈夫 （zhang1 fu0), 厉害 (li4 hai0), the second character of each by itself has non-neutral tone (烦 (fan2), 夫 （fu1, fu2), 害 (hai4)) in contrast to having a neutral tone as the second character of the word.
Are there any guidelines/rules which explain this phenomenon? How often do such words occur?
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