The past research on the subject focuses on the macro-functions of preposing in discourse and few studies have touched upon its micro-functions.

以往研究局限于置句型在语篇中的宏观,微观很少探。

From the point of view of the informativeness and textual cohesiveness of preposed theme, the stronger its informativeness, the weaker its cohesiveness, and vice versa.

置主位的信息性和衔接性来看，置主位所传递的信息新信息性越弱，语篇衔接性越强，反之亦然。