| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] [noun] be a key | 16 |
|
| 2 | [prep] [noun] is a key | 13 |
|
| 3 | [prep] [noun sg] be a key | 11 |
|
| 4 | of [noun] be a key | 8 |
|
