| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [pron] could [vb infin] [pron] have happen | 7 |
|
| 2 | [pers pn] could [vb infin] [pron] have happen | 5 |
|
| 3 | could [adv] [vb infin] [pron] have happen | 16 |
|
| 4 | could [not/n't] [vb infin] [pron] have happen | 12 |
|
| 5 | could not [vb infin] [pron] have happen | 12 |
|
| 6 | could n't [vb infin] [pron] have happen | 7 |
|
| 7 | could not [vb infin] [pron] have happen | 5 |
|
