| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | who [vb past] been exposed [prep] | 7 |
|
| 2 | [Wh pn] had been exposed [prep] | 7 |
|
| 3 | [Wh pn] [vb past] been exposed [prep] | 7 |
|
| 4 | [Wh pn] [vb past] been exposed to | 6 |
|
| 5 | [Wh pn] [vb past] been exposed to | 6 |
|
