1. 位置上的区别:as 引导的非限制性定语从句的位置比较灵活,可以放在主句前,也可以放在主句后,还可插在主句的中间;而which 引导的非限制性定语从句只能放在主句之后。例如: As is known to us all, the earth turns around the sun. The earth, as is known to us all...