| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must have been [adj] [prep] | 217 |
|
| 2 | have been [v-ing] [adj] [prep] | 211 |
|
| 3 | must have been [v-ing] [prep] | 81 |
|
| 4 | must have been [v-ing] [adj] | 22 |
|
