The accusative is a grammatical case marking the direct object. A case relator with this function is not found in many languages because the direct object relation is the syntactic counterpart to the transitive undergoer role, which is a central role and consequently sufficiently indicated by the meaning of the verb. Nevertheless, some languages do have an accusative case relator. As in the cases seen before, it may be recruited from a verb or from a case relator.

Chinese 把 bǎ is originally a verb meaning ‘grasp, hold, take’. As such, it is now only preserved in phraseological compounds like shǒubǎshǒu (hand-hold-hand) ‘by holding [someone's] hand’. Otherwise, it is grammaticalized to mark a direct object. Thus, [ [bǎ N] V] means ‘to V N’. a shows a transitive verb followed by its direct object.

b is an alternative construction with the same meaning. Here the erstwhile coverb bǎ constitutes a prepositional phrase with its complement and is positioned in front of the full verb. Again, there are constraints on this formative which distinguish it from a verb: [bǎ N] precedes V and cannot follow it. The aspect marking goes on V, not on bǎ.

Evidence for non-verbal case relators being grammaticalized to accusative again comes from Indo-European languages. The Proto-Indo-European allative case is a suffix -m. It is still used in Latin in this function (a).

However, the allative function is renewed in the language by the preposition ad seen in previous sections, while the -m case survives in allative function only with toponyms and some other place-designating nouns. Otherwise, this is the accusative marking the direct object (b). Thus, this particular grammaticalization path is constructed from synchronic evidence.

Reference

Paul, Waltraud 1982, Die Koverben im Chinesischen (with an English summary). Köln: Institut für Sprachwissenschaft der Universität (Arbeitspapier, 40).