| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | although it is difficult | 34 |
|
| 2 | as it is difficult | 22 |
|
| 3 | because it is difficult | 20 |
|
| 4 | since it is difficult | 16 |
|
| 5 | if it is difficult | 14 |
|
| 6 | though it is difficult | 14 |
|
| 7 | so it is difficult | 10 |
|
| 8 | while it is difficult | 7 |
|
| 9 | where it is difficult | 6 |
|
