| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | have become a problem | 9 |
|
| 2 | [verb] become a problem | 9 |
|
| 3 | has become a problem | 6 |
|
| 4 | [vb -s] become a problem | 6 |
|
| 5 | become a [adj] problem | 11 |
|
| 6 | become a [adj] problem | 11 |
|
