Task	Model	Language	N-gram-based	Embedding-based	Diversity	Ours
BLEU	ROUGE-L	METEOR	BERTScore	Distinct-1	Distinct-2	Ensemble
SG	M-BERT	zh->en	2.33	18.1	0.096	0.895	0.945	0.993	31.242
zh->de	2.08	13	0.125	0.716	0.962	0.995	34.057
zh->fr	1.37	13.1	0.189	0.716	0.94	0.997	30.47
zh->es	1.5	12.5	0.111	0.716	0.957	0.997	29.987
XLM	zh->en	0.77	12.3	0.074	0.882	1	1	33.839
zh->de	1.31	17.6	0.106	0.704	0.917	1	30.245
zh->fr	0.19	14.2	0.056	0.693	1	1	27.004
zh->es	0.34	17	0.049	0.701	1	1	28.576
mBART	zh->en	1.42	17.7	0.068	0.88	0.936	0.978	31.453
zh->de	0.85	9.6	0.098	0.705	0.943	0.991	33.207
zh->fr	0.76	11	0.08	0.687	0.867	0.938	26.274
zh->es	0.64	7.5	0.063	0.678	0.815	0.909	23.607
mT5	zh->en	3.04	18.9	0.098	0.899	0.967	0.995	31.665
zh->de	2.65	13.9	0.131	0.728	0.971	0.991	34.153
zh->fr	2.76	15.1	0.194	0.742	0.951	0.979	32.158
zh->es	2.72	13.6	0.119	0.738	0.964	0.988	32.053
OG	M-BERT	zh->en	6.24	29.5	0.138	0.882	0.852	0.977	29.007
zh->de	3.71	17.8	0.155	0.716	0.903	0.984	29.999
zh->fr	2.69	16.1	0.221	0.718	0.887	0.991	28.73
zh->es	3.36	18.1	0.248	0.771	0.893	0.985	30.45
XLM	zh->en	9.96	34.9	0.171	0.9	0.963	0.998	31.198
zh->de	6.81	31.9	0.206	0.759	0.974	0.998	29.542
zh->fr	9.62	33.9	0.291	0.78	0.948	0.992	28.668
zh->es	12.59	41.9	0.319	0.815	0.943	0.994	28.012
mBART	zh->en	6.04	31.3	0.129	0.895	0.981	1	30.199
zh->de	4.29	19.4	0.163	0.743	0.989	0.999	32.126
zh->fr	3.31	19.5	0.191	0.748	0.99	0.999	28.441
zh->es	3.21	14.5	0.224	0.792	0.991	1	32.106
mT5	zh->en	11.21	37.9	0.181	0.907	0.969	0.998	31.016
zh->de	7.65	24.5	0.212	0.765	0.982	0.998	32.596
zh->fr	9.67	27.4	0.292	0.785	0.966	0.994	31.326
zh->es	10.45	28.5	0.322	0.822	0.955	0.996	32.803
TG	M-BERT	zh->en	7.27	27.4	0.145	0.871	0.915	0.985	28.663
zh->de	4.86	14.2	0.145	0.701	0.923	0.991	30.084
zh->fr	4.88	18.4	0.19	0.717	0.91	0.988	27.593
zh->es	6.09	22.1	0.224	0.736	0.902	0.99	28.024
XLM	zh->en	9.6	28.4	0.174	0.879	0.958	0.992	30.079
zh->de	6.25	19.9	0.181	0.712	0.953	0.994	30.351
zh->fr	8.2	24.7	0.263	0.736	0.909	0.984	28.278
zh->es	9.12	26.8	0.261	0.748	0.903	0.991	27.991
mBART	zh->en	15.03	37.4	0.201	0.899	0.985	0.999	31.993
zh->de	1.47	9.2	0.084	0.632	0.649	0.787	23.311
zh->fr	5.41	20.1	0.167	0.701	0.822	0.901	23.772
zh->es	3.76	18.6	0.156	0.683	0.748	0.879	20.496
mT5	zh->en	10.19	30.9	0.177	0.887	0.972	0.994	30.058
zh->de	6.74	18.1	0.181	0.719	0.954	0.99	31.781
zh->fr	8.31	23.7	0.258	0.742	0.907	0.972	28.542
zh->es	9.92	26.8	0.271	0.756	0.901	0.986	29.113
Summ	M-BERT	zh->en	8.12	34	0.141	0.866	0.826	0.985	20.782
zh->de	5.84	23.7	0.176	0.712	0.815	0.984	26.296
zh->fr	6.86	27.3	0.256	0.727	0.774	0.981	22.454
zh->es	7.54	30.8	0.247	0.739	0.753	0.976	21.144
XLM	zh->en	9.13	33.8	0.164	0.869	0.742	0.942	21.267
zh->de	6	27.8	0.174	0.709	0.777	0.939	22.151
zh->fr	9.2	32.9	0.264	0.74	0.728	0.917	20.063
zh->es	9.36	34.2	0.259	0.74	0.708	0.928	19.334
mBART	zh->en	10.05	35.9	0.156	0.87	0.85	0.993	20.509
zh->de	6.71	25.5	0.192	0.712	0.813	0.988	24.843
zh->fr	8.9	31	0.267	0.741	0.798	0.988	21.728
zh->es	9.5	32.2	0.264	0.745	0.776	0.987	21.736
mT5	zh->en	4.78	29.4	0.111	0.869	0.824	0.945	23.05
zh->de	2.9	20.1	0.117	0.69	0.789	0.907	21.725
zh->fr	3.01	23.6	0.172	0.718	0.796	0.923	20.28
zh->es	4.54	27.4	0.199	0.725	0.756	0.922	19.743