“…Since then, many studies (e.g., Aoyama, 2020;Atkinson, 1987;Auerbach, 1993;Chavez, 2016;Cook, 2001;Kocaman & Aslan, 2018;Littlewood & Yu, 2011; International Journal of Linguistics ISSN 1948-5425 2020 Lucas, T., & Katz, A. 1994;Pacheco, 2018;Polio & Duff, 1994;Turnbull, 2001;Shvidko, 2017) have examined this issue from different perspectives. Some studies (e.g., Bruen & Kelly, 2017;De la Campa & Nassaji, 2009;Rolin-Ianziti & Brownlie, 2002;Sali, 2014) have investigated teachers' functions of L1 use while others (e.g., Aoyama, 2020;Sampson, 2012;Storch & Aldosari, 2010;Storch & Wigglesworth, 2003) examined functions of students' L1 use.…”