The clause element adverbial is generally optional in that it can be omitted without affecting the acceptability of the sentence and without affecting the relations of structure and meaning in the rest of the clause. Therefore the clause element of adverbial is peripheral. However, some adverbials are essential to the completion of the meaning of the verb. They cannot readily be moved from their preverbal position in a given sentence, nor can they be omitted, so they are an obligatory element of the sentence. This is exemplified by the clause pattern SAV, in which the verb compound describes a situation involving two participants, one participant is the subject referent, the other is introduced by the preposition 跟/和/与/同‘gēn/hé/yǔ/tóng’(with) or 为‘wèi’ (for), etc. The prepositional phrase functions as the obligatory adverbial of the sentence. Verb compounds belonging to this class include: 握手‘wòshǒu’ (shake hands), 见面‘jiànmiàn’ (meet, see), 打招呼‘dǎ zhāohu’ (say hello, greet somebody), 比赛‘bǐsài’ (compete, contest), 讨论‘tǎolùn’ (discuss), 辩论‘biànlùn’ (argue, debate), 请教‘qǐngjiào’ (seek advice),有关系‘yǒu guānxi’ (have connections, know sb.), etc. The verb compounds consist of a verb and an object morpheme, so they cannot combine with another noun morpheme as object, hence we cannot say, for instance, *X见面Y‘X jiànmiàn Y’, or *X结婚Y ‘X jiéhūn Y’, etc. To introduce the other party involved in the event, we have to use a prepositional phrase with the other party occurring as the prepositional object, as in 跟同学争论/打架‘gēn tóngxué zhēnglùn/dǎjià’ (to argue/fight with a classmate), 跟王小姐结婚‘gēn Wáng xiǎojie jiéhūn’ (marry Miss Wang). This type of verb compound can also be used intransitively, thus entering into the clause pattern SV, but in that case the subject NP must be plural denoting both parties involved in the event, for example: 他们去年结婚了。‘Tāmen qùnián jiéhūn le’ (They got married last year.), 哥哥和弟弟争吵以后又和好了。‘Gēge hé dìdi zhēngchǎo yǐhòu yòu héhǎo le’ (The older and younger brother became reconciled after they had argued).
 Loar, J. K. (2011). Chinese syntactic grammar: functional and conceptual principles. New York: Peter Lang.