| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | has been [art] [adj] factor | 44 |
|
| 2 | [vb -s] been a [adj] factor | 30 |
|
| 3 | [vb -s] been [art] major factor | 17 |
|
| 4 | [vb -s] been the [adj] factor | 9 |
|
| 5 | [vb -s] been [art] key factor | 6 |
|
| 6 | [vb -s] been [art] important factor | 5 |
|
| 7 | [vb -s] been an [adj] factor | 5 |
|
