| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb -s] been [v-ing] [prep] three years | 8 |
|
| 2 | [vb -s] [be] [v-ing] for three years | 8 |
|
| 3 | [vb -s] [been] [v-ing] [prep] three years | 8 |
|
| 4 | [vb -s] [be] [v-ing] [prep] three years | 8 |
|
| 5 | [vb -s] [be] [v-ing] [prep] three years | 8 |
|
| 6 | [vb -s] be [v-ing] [prep] three years | 8 |
|
| 7 | [vb -s] [be] [v-ing] for three years | 8 |
|
| 8 | has [be] [v-ing] [prep] three years | 7 |
|
