“…Natural Language Generation (NLG), is the task of generating language that is coherent and understandable to humans, has been applied to many downstream tasks such as text summary (Zhang et al, 2019a;Bar-Haim et al, 2020;Cho et al, 2020;Huang et al, 2020;Gholipour Ghalandari and Ifrim, 2020), machine translation (Li et al, 2020;Baziotis, Haddow, and Birch, 2020;Cheng et al, 2020;Zou et al, 2020), and dialogue response generation (Radford et al, 2019;Zhou et al, 2018b;Tuan, Chen, and Lee, 2019;Zhao et al, 2020;Liu et al, 2020a;Wolf et al, 2019).…”