noun +of +noun, noun+'s+ noun, or noun+noun? is there any rule? using a noun(1) describe another noun(2), I know three ways: inserting an 'of' between the two nouns, plus 's after noun(1), and puting noun(1) before noun(2). Such as: the top of the mountain; the mountain's top; the mountain top; or: the level of English the English's level the English level Are all of the three forms right?