| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | be on duty | 206 |
|
| 2 | be on duty | 206 |
|
| 3 | was on duty | 66 |
|
| 4 | be on duty | 35 |
|
| 5 | been on duty | 27 |
|
| 6 | were on duty | 25 |
|
| 7 | are on duty | 16 |
|
| 8 | 'm on duty | 12 |
|
| 9 | 's on duty | 8 |
|
| 10 | is on duty | 6 |
|
| 11 | being on duty | 6 |
|
| 12 | 're on duty | 5 |
|
