一一 (yī yī): one by one

On graduation day, the teacher called out each student's name one by one, and everyone couldn't help but cry.

After the manager checked the documents one by one, he felt reassured and signed them.

When moving house, Mom put the old photos into the box one by one, looking at each one for a long time.

The police questioned the witnesses present one by one and finally clarified the sequence of events.