I found an excellent explanation here- https://www.englishclub.com/grammar/nouns-compound.htm : Compound nouns tend to have more stress on the first word. In the phrase "pink ball", both words are equally stressed (as you know, adjectives and nouns are always stressed). In the compound noun "golf ball", the first word is stressed more (even though both words are nouns, and nouns are always stressed). Since "golf ball" is a compound noun we consider it as a single noun and so it has a single main stress - on the first word. Stress is important in compound nouns. For example, it helps us know if somebody said "a GREEN HOUSE" (a house which is painted green) or "a GREENhouse" (a building made of glass for growing plants inside). If you can recognize the emphasis on the first noun that could be a clue. If not- http://www.free-teacher-worksheets.com/support-files/compound-nouns-list.pdf I hope this helps =O)

Hello Hamed, the best way is to constantly read slightly difficult texts and identify then also try to memorize as many as you possibly can. http://www.learningdifferences.com/Main%20Page/Topics/Compound%20Word%20Lists/Compound_Word_%20Lists_complete.htm http://grammar.yourdictionary.com/parts-of-speech/nouns/compound-noun.html

Compound noun, it is an entirety。 But XX of XX, these two words are separated themselves. Each one is an entirety. To my knowledge, there are two cases. 1. Proper nouns doesn't need "of" and can be seen as compound. 2. The first word (Noun) can be used to describe the material, attribute, or other inner features of the second word (Noun) e.g. gold +ring, you just say gold ring rather than ring of gold (The ring here is made of gold.) Hope this makes sense to you. ^^