 While mass @-@ classifiers do not necessarily bear any semantic relationship to the noun with which they are used ( e.g. box and book are not related in meaning , but one can still say " a box of books " ) , count @-@ classifiers do . The precise nature of that relationship , however , is not certain , since there is so much variability in how objects may be organized and categorized by classifiers . Accounts of the semantic relationship may be grouped loosely into categorical theories , which propose that count @-@ classifiers are matched to objects solely on the basis of inherent features of those objects ( such as length or size ) , and prototypical theories , which propose that people learn to match a count @-@ classifier to a specific prototypical object and to other objects that are like that prototype . 
