| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [pron] must have been [v-ing] [prep] | 57 |
|
| 2 | they [modal v] have been [v-ing] [prep] | 24 |
|
| 3 | they [vb mod] have been [v-ing] [prep] | 24 |
|
| 4 | they must have been [verb] [prep] | 21 |
|
| 5 | they must [verb] been [v-ing] [prep] | 6 |
|
| 6 | they must have be [v-ing] [prep] | 6 |
|
| 7 | they must have been [v-ing] [prep] | 6 |
|
| 8 | they must have [be] [v-ing] [prep] | 6 |
|
| 9 | they must have [been] [v-ing] [prep] | 6 |
|
| 10 | they must have been [v-ing] [prep] | 6 |
|
