Understanding the temporal information in natural language text is an important NLP task (Verhagen et al., 2007 (Verhagen et al., , 2010 UzZaman et al., 2013; Minard et al., 2015; Bethard et al., 2016 Bethard et al., , 2017 . A crucial component is temporal relation (TempRel; e.g., before or after) extraction (Mani et al., 2006; Bethard et al., 2007; Do et al., 2012; Mirza and Tonelli, 2016; <cite>Ning et al., 2017</cite> Ning et al., , 2018a .