| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | should be concentrate [prep] | 21 |
|
| 2 | should be concentrate [prep] | 21 |
|
| 3 | should be concentrate on | 15 |
|
| 4 | should be concentrate on | 15 |
|
| 5 | should be concentrated [prep] | 13 |
|
| 6 | should be concentrating [prep] | 8 |
|
