| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must have been [verb] [adv prt] [prep] | 36 |
|
| 2 | [modal v] have been [v-ing] [adv prt] [prep] | 22 |
|
| 3 | must have been [v-ing] [adv] [prep] | 15 |
|
| 4 | must [vb infin] been [v-ing] [adv prt] [prep] | 9 |
|
| 5 | must have [been] [v-ing] [adv prt] [prep] | 9 |
|
| 6 | must have been [v-ing] [adv prt] [prep] | 9 |
|
| 7 | must [verb] been [v-ing] [adv prt] [prep] | 9 |
|
| 8 | must have be [v-ing] [adv prt] [prep] | 9 |
|
| 9 | must have [be] [v-ing] [adv prt] [prep] | 9 |
|
