| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | operate at [art] lower [noun sg] | 7 |
|
| 2 | operate at [art] lower [noun sg] | 7 |
|
| 3 | operate at a lower [noun sg] | 6 |
|
| 4 | operate at a lower [noun sg] | 6 |
|
