Past studies in education showed that higher-level questions, in contrast to simple factoid questions, have more educational benefits for reading comprehension (Anderson and Biddle, 1975;Andre, 1979;Hamaker, 1986).
most of existing approaches to question generation have focused on generating questions from a single sentence, relying heavily on syntax and shallow semantics with an emphasis on grammaticality (Mitkov and Ha, 2003;Chen et al., 2009;Heilman and Smith, 2010;Curto et al., 2011;Becker et al., 2012;Lindberg et al., 2013;Mazidi and Nielsen, 2014).