| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it must [vb infin] been [adv] [prep] | 7 |
|
| 2 | it must [vb infin] be [adv] [prep] | 7 |
|
| 3 | it must have be [adv] [prep] | 7 |
|
