| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | which has [been] [v-ing] on for | 6 |
|
| 2 | which [vb -s] [been] [v-ing] on for | 6 |
|
| 3 | which [vb -s] been [v-ing] on for | 6 |
|
| 4 | which [vb -s] [been] going on for | 5 |
|
