| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | system be [vb pp] [prep] be | 30 |
|
| 2 | system be [vb pp] to [be] | 30 |
|
| 3 | system is [vb pp] [prep] [be] | 20 |
|
| 4 | system was [vb pp] [prep] [be] | 6 |
|
