| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a [noun] [Wh det] | 7702 |
|
| 2 | [prep] a [noun] system | 623 |
|
| 3 | a [noun] system [Wh det] | 101 |
|
| 4 | [prep] a system [Wh det] | 91 |
|
| 5 | [prep] [noun] system [Wh det] | 16 |
|
