N-gram | Seq2Seq + Attention | T5-PEGASUS-PGN | 标准摘要 |
1-gram | 27% | 22% | 21% |
2-gram | 19% | 7% | 8% |
3-gram | 18% | 2% | 3% |
4-gram | 12% | 2% | 1% |