| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | the key to [noun] [noun sg] | 17 |
|
| 2 | the key to [noun sg] [noun sg] | 14 |
|
| 3 | the key to understanding [noun sg] | 5 |
|
| 4 | the key to understanding [noun sg] | 5 |
|
