| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | problem [prep] how | 152 |
|
| 2 | problem [prep] how | 152 |
|
| 3 | problem of how | 145 |
|
| 4 | problem of how | 145 |
|
| 5 | problem [prep] how | 137 |
|
| 6 | problems [prep] how | 15 |
|
