| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | have been [v-ing] [prep] a | 521 |
|
| 2 | they have been [v-ing] [prep] | 256 |
|
| 3 | they have been [prep] a | 32 |
|
| 4 | they have been [v-ing] a | 27 |
|
