| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | who [verb] been president [prep] | 9 |
|
| 2 | [Wh pn] have been president [prep] | 9 |
|
| 3 | [Wh pn] [verb] been president of | 8 |
|
| 4 | [Wh pn] had been president [prep] | 8 |
|
| 5 | [Wh pn] [vb past] been president [prep] | 8 |
|
