| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb mod] be kept clean | 12 |
|
| 2 | [modal v] be kept clean | 12 |
|
| 3 | to be kept clean | 11 |
|
| 4 | [prep] be kept clean | 11 |
|
| 5 | [prep] be kept clean | 11 |
|
| 6 | to be kept clean | 11 |
|
| 7 | must be kept clean | 6 |
|
| 8 | must be kept clean | 6 |
|
| 9 | be kept clean [conj] | 9 |
|
| 10 | be kept clean and | 7 |
|
| 11 | be kept clean [coord] | 7 |
|
| 12 | be kept clean and | 7 |
|
