not all stems occur in the same mode-aspect combinations. Additionally, the different stem forms of different verbs are formed in different ways. Classificatory verbs Southern Athabaskan languages have verb stems that classify a particular object by its shape or other physical characteristics in addition to describing the movement or state of the object. These are known in Athabaskan linguistics as classificatory verb stems. These are usually identified by an acronym label. There are 11 primary classificatory "handling" verbs stems in Navajo which are listed below (given in the perfective mode). Other Southern Athabaskan languages have a slightly different set of stems. To compare with English, Navajo has no single verb that corresponds to the English word give. In order to say the equivalent of Give me some hay! the Navajo verb níłjool (NCM) must be used, while for Give me a cigarette! the verb nítįįh (SSO) must be used. The English verb give is expressed by 11 verbs in Navajo, depending on the characteristics of the given object. In addition to defining the physical properties of the object, primary classificatory verb stems also can distinguish between the manner of movement of the object. The stems can then be grouped into three categories: handling propelling free flight Handling includes actions such as carrying, lowering, and taking. Propelling includes tossing, dropping, and throwing. Free flight includes falling, and flying through space. Using an example for the SRO category Navajo has -'ą́ to handle (a round object), -ne' to throw (a round object), and -l-ts'id (a round object) moves independently. In addition, Southern Athabaskan languages also have other somewhat similar verb stems that Young & Morgan (1987) call secondary classificatory verbs. (The term classifier is used in Athabaskan linguistics to refer to a prefix that indicates transitivity or acts as a thematic prefix, and as such is somewhat of a misnomer. These transitivity classifiers are not involved in the classificatory verb stems' classification of nouns and are not related in any way to the noun classifiers found in Chinese or Thai). yi-/bi- alternation (animacy) Like most Athabaskan languages, Southern Athabaskan languages show various levels of animacy in its grammar, with certain nouns taking specific verb forms according to their rank in this animacy hierarchy. For instance, Navajo nouns can be ranked by animacy on a continuum from most animate (a human or lightning) to least animate (an abstraction) (Young & Morgan 1987: 65-66):