| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | be [vb pp] refer to | 85 |
|
| 2 | be [vb pp] to refer to | 81 |
|
| 3 | be used refer to | 48 |
|
| 4 | is [vb pp] refer to | 31 |
|
| 5 | be [vb pp] refer to | 27 |
|
| 6 | been [vb pp] refer to | 8 |
|
| 7 | are [vb pp] refer to | 8 |
|
| 8 | was [vb pp] refer to | 5 |
|
