| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | be [v-ing] [prep] [adv] a year | 5 |
|
| 2 | [be] [v-ing] [prep] [adv] a year | 5 |
|
| 3 | [v-ing] [prep] [adv] [n mass] a year | 12 |
|
| 4 | [v-ing] [prep] [adv] [noun] a year | 12 |
|
