Adverbials of definite frequency, which denote the period of time by which the frequency is measured, are ordered before the verbs they modify. If they cooccur with expressions like 两次‘liǎngbiàn’ (twice) and 三次‘sāncì’ (three times) (they are termed action-measure complement (AMC) in Chinese grammar), the latter is placed after the verb, though both can be considered as definite frequency expressions. Why is this case? Because adverbials of period frequency signify the temporal scope within which the action or state named by the verb takes place or obtains, so they are ordered before the verb in terms of the PTSC; while AMC may be conceived as expressing the measurement in number of times an action or event was/will be conducted. According to Chinese conceptual structures, the counting of an event is possible only when the event was or will be completed or terminated, so such phrases follow the verb in terms of the PTS as complements. The two different positions of the two types of semantically similar expressions further testify to the fact that the PTS and PTSC play a crucial role in ordering clause elements in a sentence.
 Loar, J. K. (2011). Chinese syntactic grammar: functional and conceptual principles. New York: Peter Lang.