| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [noun pl] could [vb infin] their | 163 |
|
| 2 | [noun pl] could [verb] their | 163 |
|
| 3 | [noun pl] [modal v] improve their | 16 |
|
| 4 | [noun] could improve their | 8 |
|
| 5 | [noun pl] could improve [pron] | 5 |
|
| 6 | [noun pl] could improve their | 5 |
|
