| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [is] used [prep] [art] | 600 |
|
| 2 | system [is] [prep] [art] | 25 |
|
| 3 | system [is] used [prep] | 16 |
|
| 4 | system used [prep] [art] | 16 |
|
