| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [noun] [vb -s] a [adj] challenge to | 9 |
|
| 2 | [noun sg] [vb -s] a [adj] challenge to | 6 |
|
| 3 | [vb -s] a [adj] challenge to the | 12 |
|
| 4 | [vb -s] a [adj] challenge to the | 12 |
|
| 5 | [vb -s] a [adj] challenge to [art] | 12 |
|
| 6 | [vb -s] a [adj] challenge to [art] | 12 |
|
| 7 | [vb -s] a [adj] challenge to [adj] | 5 |
|
