“…Besides, it is also impossible to classify the verbs triggering the infinitive complement construction from the verbs triggering the gerund complement construction without consulting with a good dictionary(Swan, 2005). Finally, it is more interesting to look specifically at L1Thai learners' production and perception of English infinitive and gerund complement constructions because it can possibly be said that there are no parallel of the infinitive and the gerund verbal complement constructions between English and Thai(Lekawatana et al, 1969; Mallikamas, 2010).To the best of the researcher's knowledge, there has been a lot of research exploring the acquisition of infinitive and gerund complements among L2 English learners from different native languages(Almulla, 2015;Cook, 1996;Mazurkewich, 1988;Schwartz & Causarano, 2007;Shirahata, 1990; Wakabayashi, Hokari, Haniu, Fujimoto, & Kimura, 2016), including L1 Thai learners(Kitikanan, 2011;Samana, 2005). However, while most of the studies agreed that L2 learners of English acquired the infinitive complements before the gerund complements(Almulla, 2015;Cook, 1996;Mazurkewich, 1988;Samana, 2005;Schwartz & Causarano, 2007;Shirahata, 1990;Wakabayashi et al, 2016), one research findings showed a contradiction…”