The key items in realizing adverbials of backward span are prepositions ‘zì…yǐlái’ (since), ‘dǎ…shíhou qǐ’ (since…), ‘cóng…qǐ’ (from…), ‘cóng…yǐlái’姓(from…), they introduce either a prepositional phrase or a clause. The backward span indicates the stretch of time back from the speaker’s ‘now’; the span occurs with verbs describing continuous actions or states. It is often used with the perfective aspect particle ‘le’, which denotes that the action or state extends up to the ‘now’ of the speaker (that is, the time of ‘primary concern’ to the speaker, which may be ‘then’ if it is a past time that is of primary concern).
Please refer to Figure V and sentence (1a).
Tā cóng háitóng qǐ jiù xǐhuan huà gāngbǐ huà le .
(He has liked to draw with a pen since he was a child.)
Zhōngguó nóngyè, zìgǔyǐlái zài shuǐ de tiáojiàn fāngmiàn yī zhí bù lǐxiǎng.
(Since ancient times, the water supply has not been ideal for China’s agriculture.)
Dàyuē liǎngsuì bàn qǐ, értóng kěyǐ yòng fùhéjù biǎodá zìjǐ de yìsi.
(From about two and a half years old, a child is capable of expressing his ideas by using complex sentences.)
Jìn bǎi nián lái, wǒmen dàdàdi luòhòu le .
(We have been left far behind for the past one hundred years.)
The adverbials of backward span ‘cóng…qǐ’ (from…) and ‘zì…yǐlái’ (since…) specify a span of time and also mark the starting point, in (1a), for example, the starting point is ‘childhood’. In (1d) the time span expressed by the adverbial phrase ‘jìn bǎinián lái’ (in recent one hundred years), however, is ‘unlocated’ in the past, but because the clause has the verb ‘luòhòu’ (leg behind) in the perfective aspect, we know that the time span extends to the ‘now’, and the hearer is able to count back and calculate the proximate initial point in the span. All backward time spans are used with continuous actions and states.
 Loar, J. K. (2011). Chinese syntactic grammar: functional and conceptual principles. New York: Peter Lang.