| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it must have be [prep] [det] | 15 |
|
| 2 | it must have been [prep] [det] | 15 |
|
| 3 | it must have be [prep] this | 5 |
|
| 4 | it must have be [prep] that | 5 |
|
