| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [ex0] must [prep] been | 9 |
|
| 2 | [ex0] must [prep] [been] | 9 |
|
| 3 | there must [prep] [been] | 9 |
|
| 4 | [ex0] must of [been] | 9 |
|
