| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [pron] have been on duty [prep] | 7 |
|
| 2 | [noun] have been on duty [prep] | 5 |
|
| 3 | have been on duty [prep] [art] | 7 |
|
| 4 | have been on duty [prep] [art] | 7 |
|
| 5 | have been on duty [prep] the | 6 |
|
| 6 | have been on duty [prep] the | 6 |
|
