The word “diary” comes from the Latin word “diarium”, which means “daily allowance”. 1. And it is used for business notes, planning activities, keeping track of scheduled appointments, or documenting what has already happened. Some doctors suggest that writing in a diary is a good form of self-study.
从上述原文可知，it指代的是名词diary。三个doing结构由并列连词or连接，都是解释business notes的，也就是说这是notes的同位语。所以三个doing结构都是动名词短语作同位语，不可能是现在分词作状语或定语。writing in a diary是that从句的主语，也是动名词短语。
动名词在句子中作名词性成分，如主语、宾语、表语、同位语。现在分词在句子中作形容词性成分，如状语、定语、宾补。你的句子中的doing形式都在名词性成分的位置上（同位语和主语），所以都是动名词。
