| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | system was [art] | 67 |
|
| 2 | system was a | 35 |
|
| 3 | system was the | 32 |
|
| 4 | system was the | 32 |
|
| 5 | system was a | 30 |
|
| 6 | system was an | 5 |
|
