1·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 研究局限于前置句型在语篇中的宏观功能，其微观功能很少探讨。
2·The present dissertation investigates pragmatic constraints on preposing constructions in the acquisition of English as a foreign language (EFL) by Chinese-speaking learners.
本文从英语过去时的距离性实质出发研究一般过去时 （包括情态动词的过去时形式 ）用来表示客气礼貌的语用机制。