| 1 | I knew him before. | |
| 2 | In the past, I used to like going to bookstores to read. | |
| 3 | In the past, I could run 10 kilometers without stopping. | |
| 4 | We used to have a cat in our family in the old days. | |
| 5 | Trains used to be the main means of transportation in the past. |
