The Principle of Temporal Sequence (PTS) was proposed by linguist Tai in 1985. The principle states: “The relative word order between syntactic units is determined by the temporal order of the states they represent in the conceptual world.” The PTS governs the position of a temporal adverbial (a) and a duration.
complement (b) as in:
Wǒmen sān diǎn kāi huì.
(We’ll have a meeting at three o’clock.)
Wǒmen kāi huì kāi le sān gè zhōngtóu.
(We had a meeting for three hours.)
‘sān diǎn’ (three o’clock) denotes the point in time when an event begins or happens. It is ordered before the verb ‘kāi huì’ (hold a meeting) in terms of the PTS, for only when time progresses to three o’clock can the meeting begin. By contrast, ‘sān gè zhōngtóu’ (three hours) in (6b) denotes the continuation of the meeting. It has been observed by Tai (1989a) that there seems to be an iconic element in the syntactic phenomenon in that the reduplication of the verb ‘kāi huì kāi le’ may be said to mirror the dragging out of the activity or the process associated with the verb. In terms of temporal sequence, we may regard the continuous event of holding the meeting as consisting of three temporally ordered parts, with the first part denoting the beginning of the event, the second part the continuation of the event, and the third part measurement of the extension of the action in terms of time.
 Loar, J. K. (2011). Chinese syntactic grammar: functional and conceptual principles. New York: Peter Lang.