“为”字在古汉语中曾用作系词,它产生的动因在于弥补无系词判断句充当句子成分或者充当复句的分句时表意的不足,它是由动词“为”虚化而来的,它可以在动词“为”的不同义项上,在不同的句法结构里虚化为系词。 The word “for” was used as a copula in ancient Chinese, and the motivation for it is to make up for the lack of meaning when the nonsense sentence is used as a sentence component or as a clause of a complex sentence. It consists of the verb From the empty, it can be in the verb “for ” on the different items, in different syntax structure into a co-word.