build it
| simple past of BE + ING-form of verb | I was dreaming you were riding it was raining they were sailing |
| ING-form = infinitive + ING | walk + ing = walking understand + ing = understanding teach + ing = teaching |
| special: drop the end -E of the infinitive | make + ing = making write + ing = writing make + ing = making |
| extra: double the ending consonant to keep the sound short |
sit + ing = sitting begin = ing = beginning stop = ing = stopping |