| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | have been [prep] a | 790 |
|
| 2 | have been operate [prep] | 63 |
|
| 3 | have operate [prep] a | 27 |
|
| 4 | been operate [prep] a | 7 |
|
| 5 | have been operate a | 6 |
|
