| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | may have [been] [verb] for | 30 |
|
| 2 | may have [been] [vb pp] for | 27 |
|
| 3 | may have [been] used [prep] | 22 |
|
| 4 | may have [been] used [prep] | 22 |
|
| 5 | [modal v] have [been] used for | 15 |
|
| 6 | may [verb] [been] used for | 5 |
|
| 7 | may have [been] used for | 5 |
|
| 8 | may have [be] used for | 5 |
|
| 9 | may have [been] use for | 5 |
|
