| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | have referred to | 188 |
|
| 2 | have refer to | 68 |
|
| 3 | has refer to | 47 |
|
| 4 | had refer to | 39 |
|
| 5 | have to refer to | 28 |
|
| 6 | 've refer to | 16 |
|
| 7 | have refer to | 16 |
|
| 8 | having refer to | 16 |
|
| 9 | 's refer to | 9 |
|
